The safety and efficacy of a combined diode laser and bipolar radiofrequency compared with combined infrared light and bipolar radiofrequency for skin rejuvenation.

Science.gov (United States)

Choi, Yeon Jin; Lee, Jung Yeon; Ahn, Ji Young; Kim, Myeung Nam; Park, Mi Youn

2012-01-01

As the demand for noninvasive procedures for skin rejuvenation is increasing, combined diode laser and radiofrequency and combined infrared and radiofrequency devices have recently emerged. To compare Polaris WRA(TM), a combination device of diode light and RF, and ReFirme ST(TM), a combination device of infrared and bipolar RF, in terms of safety and efficacy on skin rejuvenation. Fourteen Korean volunteers of skin type II-IV, with facial laxity and periorbital rhytids, received three treatments at 3-week intervals with combined diode laser and bipolar radiofrequency (laser fluence 30 J/cm2, RF fluence 90 J/cm3) on the right half of their faces and combined infrared light and bipolar radiofrequency (RF fluence 120 J/cm3) on the left half of their faces. Clinical photos of front and bilateral sides of the subjects' faces were taken at baseline and at 6, 9, 12 weeks after the treatment initiation. The investigators' and the subjects' global assessments were performed. There is no statistically significant difference in the overall outcome between Polaris WRA(TM) and Refirme ST(TM) based on pre- and post-treatment objective measurements. Polaris WRA(TM) was more effective than Refirme ST(TM) at reducing wrinkles when therapeutic results of the two appliances were compared based on the patient satisfaction measurements. After the treatment with both instruments, histological increase in the production and rearrangement of collagen fibers at the dermal layer was observed. The density of the collagen fibers was more increased with the Polaris WRA(TM)-treated facial area than that of Refirme ST(TM). Treatment was generally well tolerated, and there was no serious complication. In this study, both the lasers appeared to be safe, and effective methods for treating skin laxity and facial wrinkles. Combined diode laser and radiofrequency was more effective than combined infrared and radiofrequency at reducing wrinkles and pores when the therapeutic results of both the

Long-term reduction in infrared autofluorescence caused by infrared light below the maximum permissible exposure.

Science.gov (United States)

Masella, Benjamin D; Williams, David R; Fischer, William S; Rossi, Ethan A; Hunter, Jennifer J

2014-05-20

Many retinal imaging instruments use infrared wavelengths to reduce the risk of light damage. However, we have discovered that exposure to infrared illumination causes a long-lasting reduction in infrared autofluorescence (IRAF). We have characterized the dependence of this effect on radiant exposure and investigated its origin. A scanning laser ophthalmoscope was used to obtain IRAF images from two macaques before and after exposure to 790-nm light (15-450 J/cm(2)). Exposures were performed with either raster-scanning or uniform illumination. Infrared autofluorescence images also were obtained in two humans exposed to 790-nm light in a separate study. Humans were assessed with direct ophthalmoscopy, Goldmann visual fields, multifocal ERG, and photopic microperimetry to determine whether these measures revealed any effects in the exposed locations. A significant decrease in IRAF after exposure to infrared light was seen in both monkeys and humans. In monkeys, the magnitude of this reduction increased with retinal radiant exposure. Partial recovery was seen at 1 month, with full recovery within 21 months. Consistent with a photochemical origin, IRAF decreases caused by either raster-scanning or uniform illumination were not significantly different. We were unable to detect any effect of the light exposure with any measure other than IRAF imaging. We cannot exclude the possibility that changes could be detected with more sensitive tests or longer follow-up. This long-lasting effect of infrared illumination in both humans and monkeys occurs at exposure levels four to five times below current safety limits. The photochemical basis for this phenomenon remains unknown. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Mid infrared lasers for remote sensing applications

Energy Technology Data Exchange (ETDEWEB)

Walsh, Brian M., E-mail: brian.m.walsh@nasa.gov [NASA Langley Research Center, Hampton, VA 23681 (United States); Lee, Hyung R. [National Institute of Aerospace, Hampton, VA 23666 (United States); Barnes, Norman P. [Science Systems and Applications, Inc., Hampton, VA 23666 (United States)

2016-01-15

To accurately measure the concentrations of atmospheric gasses, especially the gasses with low concentrations, strong absorption features must be accessed. Each molecular species or constituent has characteristic mid-infrared absorption features by which either column content or range resolved concentrations can be measured. Because of these characteristic absorption features the mid infrared spectral region is known as the fingerprint region. However, as noted by the Decadal Survey, mid-infrared solid-state lasers needed for DIAL systems are not available. The primary reason is associated with short upper laser level lifetimes of mid infrared transitions. Energy gaps between the energy levels that produce mid-infrared laser transitions are small, promoting rapid nonradiative quenching. Nonradiative quenching is a multiphonon process, the more phonons needed, the smaller the effect. More low energy phonons are required to span an energy gap than high energy phonons. Thus, low energy phonon materials have less nonradiative quenching compared to high energy phonon materials. Common laser materials, such as oxides like YAG, are high phonon energy materials, while fluorides, chlorides and bromides are low phonon materials. Work at NASA Langley is focused on a systematic search for novel lanthanide-doped mid-infrared solid-state lasers using both quantum mechanical models (theoretical) and spectroscopy (experimental) techniques. Only the best candidates are chosen for laser studies. The capabilities of modeling materials, experimental challenges, material properties, spectroscopy, and prospects for lanthanide-doped mid-infrared solid-state laser devices will be presented. - Highlights: • We discuss mid infrared lasers and laser materials. • We discuss applications to remote sensing. • We survey the lanthanide ions in low phonon materials for potential. • We present examples of praseodymium mid infrared spectroscopy and laser design.

Estimating optical feedback from a chalcogenide fiber in mid-infrared quantum cascade lasers

Directory of Open Access Journals (Sweden)

L. Jumpertz

2016-10-01

Full Text Available The amount of optical feedback originating from a chalcogenide fiber used to couple light from a mid-infrared quantum cascade laser is evaluated experimentally. Threshold reduction measurements on the fibered laser, combined with an analytical study of a rate equations model of the laser under optical feedback, allow estimating the feedback strength between 11% and 15% depending on the fiber cleavage quality. While this remains below the frontier of the chaotic regime, it is sufficient to deeply modify the optical spectrum of a quantum cascade laser. Hence for applications such as gas spectroscopy, where the shape of the optical spectrum is of prime importance, the use of mid-infrared optical isolators may be necessary for fibered quantum cascade lasers to be fully exploited.

Coherent infrared radiation from the ALS generated via femtosecond laser modulation of the electron beam

International Nuclear Information System (INIS)

Byrd, J.M.; Hao, Z.; Martin, M.C.; Robin, D.S.; Sannibale, F.; Schoenlein, R.W.; Venturini, M.; Zholents, A.A.; Zolotorev, M.S.

2004-01-01

Interaction of an electron beam with a femtosecond laser pulse co-propagating through a wiggler at the ALS produces large modulation of the electron energies within a short ∼100 fs slice of the electron bunch. Propagating around the storage ring, this bunch develops a longitudinal density perturbation due to the dispersion of electron trajectories. The length of the perturbation evolves with a distance from the wiggler but is much shorter than the electron bunch length. This perturbation causes the electron bunch to emit short pulses of temporally and spatially coherent infrared light which are automatically synchronized to the modulating laser. The intensity and spectra of the infrared light were measured in two storage ring locations for a nominal ALS lattice and for an experimental lattice with the higher momentum compaction factor. The onset of instability stimulated by laser e-beam interaction had been discovered. The infrared signal is now routinely used as a sensitive monitor for a fine tuning of the laser beam alignment during data accumulation in the experiments with femtosecond x-ray pulses

Absorption Spectroscopy in Hollow-Glass Waveguides Using Infrared Diode Lasers[4817-25

International Nuclear Information System (INIS)

Blake, Thomas A.; Kelly, James F.; Stewart, Timothy L.; Hartman, John S.; Sharpe, Steven W.; Sams, Robert L.; Alan Fried

2002-01-01

Near- and mid-infrared diode lasers combined with flexible, hollow waveguides hold the promise of light weight, field portable, fast response gas sensors. The advantages of using the waveguides compared to White or Herriott multireflection cells include a small gas volume, a high photon fill factor in the waveguide, which increases molecule-light interactions, and reduction or elimination of optical fringing, which usually sets the practical limit of detectivity in absorption spectroscopy. Though hollow waveguides have been commercially available for several years, relatively few results have been reported in the literature. We present here results from our laboratory where we have injected infrared laser light into straight and coiled lengths of hollow waveguides and performed direct and wavelength modulated absorption spectroscopy on nitrous oxide, ethylene, and nitric oxide. Using a 1 mm bore, 3 meter long coiled waveguide coated for the near infrared, nitrous oxide transitions near 6595 cm-1 were observed under flowing conditions. Signal-to-noise ratios on the order of 1500:1 with RMS noise equal to 2 X 10-5 were measured. In the mid-infrared light from either a 10.1 or 5.3 micron lead salt diode laser was injected into a three meter length of 1 mm bore hollow waveguide coated for the mid-infrared. The waveguide was coiled with one loop at a diameter of 52 cm. Ethylene transitions were observed in the vicinity of 985 cm-1 with a static fill of 0.2 Torr of pure ethylene in the waveguide and nitric oxide transitions were observed in the vicinity of 1906 cm-1 using either a flow or a static fill of 1 ppm NO in nitrogen. In direct absorption the NO transitions are observed to have a signal-to-noise of approximately 5:1 for transitions with absorbances on the order of 10-3. Using wavelength modulated techniques the signal-to-noise ratio improves at least an order of magnitude. These encouraging results indicate that waveguides can be used for in situ gas monitoring

Infrared emission from a polycyclic aromatic hydrocarbon (PAH) excited by ultraviolet laser

International Nuclear Information System (INIS)

Cherchneff, I.; Barker, J.R.

1989-01-01

The infrared fluorescence spectrum from the C-H stretch modes of vibrationally excited azulene (C10H8), a PAH was measured in the laboratory. PAHs are candidates as carriers of the unidentified infrared emission bands that are observed in many astronomical objects associated with dust and ultraviolet light. In the present experiment, gas phase azulene was excited with light from a 308 nm pulsed laser, and the infrared emission spectrum was time-resolved and wavelength-resolved. Moreover, the infrared absorption spectrum of gas phase azulene was obtained using an FTIR spectrometer. The laboratory emission spectrum resembles observed infrared emission spectra from the interstellar medium, providing support for the hypothesis that PAHs are the responsible carriers. The azulene C-H stretch emission spectrum is more asymmetric than the absorption spectrum, probably due to anharmonicity of levels higher than nu = 1. 36 refs

Infrared laser system

International Nuclear Information System (INIS)

Cantrell, C.D.; Carbone, R.J.

1977-01-01

An infrared laser system and method for isotope separation may comprise a molecular gas laser oscillator to produce a laser beam at a first wavelength, Raman spin flip means for shifting the laser to a second wavelength, a molecular gas laser amplifier to amplify said second wavelength laser beam to high power, and optical means for directing the second wavelength, high power laser beam against a desired isotope for selective excitation thereof in a mixture with other isotopes. The optical means may include a medium which shifts the second wavelength high power laser beam to a third wavelength, high power laser beam at a wavelength coincidental with a corresponding vibrational state of said isotope and which is different from vibrational states of other isotopes in the gas mixture

Low-intensity infrared laser effects on zymosan-induced articular inflammatory response

Science.gov (United States)

Januária dos Anjos, Lúcia Mara; da Fonseca, Adenilson d. S.; Gameiro, Jacy; de Paoli, Flávia

2015-03-01

Low-level therapy laser is a phototherapy treatment that involves the application of low power light in the red or infrared wavelengths in various diseases such as arthritis. In this work, we investigated whether low-intensity infrared laser therapy could cause death by caspase-6 apoptosis or DNA damage pathways in cartilage cells after zymosaninduced articular inflammatory process. Inflammatory process was induced in C57BL/6 mouse by intra-articular injection of zymosan into rear tibio-tarsal joints. Thirty animals were divided in five groups: (I) control, (II) laser, (III) zymosan-induced, (IV) zymosan-induced + laser and (V). Laser exposure was performed after zymosan administration with low-intensity infrared laser (830 nm), power 10 mW, fluence 3.0 J/cm2 at continuous mode emission, in five doses. Twenty-four hours after last irradiation, the animals were sacrificed and the right joints fixed and demineralized. Morphological analysis was observed by hematoxylin and eosin stain, pro-apoptotic (caspase-6) was analyzed by immunocytochemistry and DNA fragmentation was performed by TUNEL assay in articular cartilage cells. Inflammatory process was observed in connective tissue near to articular cartilage, in IV and V groups, indicating zymosan effect. This process was decreased in both groups after laser treatment and dexamethasone. Although groups III and IV presented higher caspase-6 and DNA fragmentation percentages, statistical differences were not observed when compared to groups I and II. Our results suggest that therapies based on low-intensity infrared lasers could reduce inflammatory process and could not cause death by caspase-6 apoptosis or DNA damage pathways in cartilage cells after zymosan-induced articular inflammatory process.

New infrared solid state laser materials for CALIOPE

International Nuclear Information System (INIS)

DeLoach, L.D.; Page, R.H.; Wilke, G.D.

1994-01-01

Tunable infrared laser light may serve as a useful means by which to detect the presence of the targeted effluents. Since optical parametric oscillators (OPOs) have proven to be a versatile method of generating coherent light from the ultraviolet to the mid-infrared, this technology is a promising choice by which to service the CALIOPE applications. In addition, since some uncertainty remains regarding the precise wavelengths and molecules that will be targeted, the deployment of OPOs retains the greatest amount of wavelength flexibility. Another approach that the authors are considering is that of generating tunable infrared radiation directly with a diode-pumped solid state laser (DPSSL). One important advantage of a DPSSL is that it offers flexible pulse format modes that can be tailored to meet the needs of a particular application and target molecule. On the other hand, direct generation by a tunable DPSSL will generally be able to cover a more limited wavelength range than is possible with OPO technology. In support of the CALIOPE objectives the authors are exploring the potential for laser action among a class of materials comprised of transition metal-doped zinc chalcogenide crystals (i.e., ZnS, ZnSe and ZnTe). The Cr 2+ , Co 2+ and Ni 2+ dopants were selected as the most favorable candidates, on the basis of their documented spectral properties in the scientific literature. Thus far, the authors have characterized the absorption and emission properties of these ions in the ZnS and ZnSe crystals. The absorption spectra are used to determine the preferred wavelength at which the crystal should be pumped, while the emission spectra reveal the extent of the tuning range potentially offered by the material. In addition, measurements of the emission lifetime as a function of temperature turn out to be quite useful, since this data is suggestive of the room temperature emission yield

Mid-Infrared Lasers

Data.gov (United States)

National Aeronautics and Space Administration — Mid infrared solid state lasers for Differential Absorption Lidar (DIAL) systems required for understanding atmospheric chemistry are not available. This program...

Light/laser therapy in the treatment of acne vulgaris.

Science.gov (United States)

Nouri, Keyvan; Villafradez-Diaz, L Magaly

2005-12-01

Acne vulgaris is one of the most prevalent skin diseases known. As common as this condition is, the social and psychological consequences are limitless. Although current treatments are available and include topical or oral antibiotics, it is crucial to develop a less risky and more effective therapy such as light/laser therapy. This article focuses specifically on the benefits of the light/laser treatment on acne vulgaris. Porphyrins accumulated in the bacteria, Propionibacterium acnes, one of the etiologic factors involved in the pathogenesis, allows phototherapy to be a successful modality. They have specific absorption peaks at which lasers have optimal effects. The longer the wavelength of the light is, the deeper its penetration and thus the greater its damage to the sebaceous glands. Although blue light is best for the activation of porphyrins, red light is best for deeper penetration and an anti-inflammatory effect. Ultraviolet (UV) light, although it may have initial an anti-inflammatory effects, has been proven to be potentially carcinogenic and have adverse effects such as aging (by UV-A) and burning (by UV-B). Previous studies indicate successful long-term intervention and selective damage of the sebaceous glands by using a diode laser with indocyanine green (ICG) dye. Mid-infrared lasers have been found to decrease lesion counts while also reducing the oiliness of skin and the scarring process. Nonablative laser treatment of acne scars using the Er:YAG laser with a short-pulsed mode has been successful in reducing the appearance of scars by stimulating neocollagenesis. The light/laser therapy has started to be explored with promising results in highly selected patients that require further investigation in greater populations and well-designed protocols.

Efficient, High-Power Mid-Infrared Laser for National Securityand Scientific Applications

Energy Technology Data Exchange (ETDEWEB)

Kiani, Leily S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-11-02

The LLNL fiber laser group developed a unique short-wave-infrared, high-pulse energy, highaverage- power fiber based laser. This unique laser source has been used in combination with a nonlinear frequency converter to generate wavelengths, useful for remote sensing and other applications in the mid-wave infrared (MWIR). Sources with high average power and high efficiency in this MWIR wavelength region are not yet available with the size, weight, and power requirements or energy efficiency necessary for future deployment. The LLNL developed Fiber Laser Pulsed Source (FiLPS) design was adapted to Erbium doped silica fibers for 1.55 μm pumping of Cadmium Silicon Phosphide (CSP). We have demonstrated, for the first time optical parametric amplification of 2.4 μm light via difference frequency generation using CSP with an Erbium doped fiber source. In addition, for efficiency comparison purposes, we also demonstrated direct optical parametric generation (OPG) as well as optical parametric oscillation (OPO).

Modification in oxidative processes in muscle tissues exposed to laser- and light-emitting diode radiation.

Science.gov (United States)

Monich, Victor A; Bavrina, Anna P; Malinovskaya, Svetlana L

2018-01-01

Exposure of living tissues to high-intensity red or near-infrared light can produce the oxidative stress effects both in the target zone and adjacent ones. The protein oxidative modification (POM) products can be used as reliable and early markers of oxidative stress. The contents of modified proteins in the investigated specimens can be evaluated by the 2,4-dinitrophenylhydrazine assay (the DNPH assay). Low-intensity red light is able to decrease the activity of oxidative processes and the DNPH assay data about the POM products in the biological tissues could show both an oxidative stress level and an efficiency of physical agent protection against the oxidative processes. Two control groups of white rats were irradiated by laser light, the first control group by red light and the second one by near-infrared radiation (NIR).Two experimental groups were consequently treated with laser and red low-level light-emitting diode radiation (LED). One of them was exposed to red laser light + LED and the other to NIR + LED. The fifth group was intact. Each group included ten animals. The effect of laser light was studied by methods of protein oxidative modifications. We measured levels of both induced and spontaneous POM products by the DNPH assay. The dramatic increase in levels of POM products in the control group samples when compared with the intact group data as well as the sharp decrease in the POM products in the experimental groups treated with LED low-level light were statistically significant (p ≤ 0.05). Exposure of skeletal muscles to high-intensity red and near-infrared laser light causes oxidative stress that continues not less than 3 days. The method of measurement of POM product contents by the DNPH assay is a reliable test of an oxidative process rate. Red low-intensity LED radiation can provide rehabilitation of skeletal muscle tissues treated with high-intensity laser light.

Nucleotide excision repair pathway assessment in DNA exposed to low-intensity red and infrared lasers

International Nuclear Information System (INIS)

Fonseca, A.S.; Campos, V.M.A.; Magalhaes, L.A.G.; Paoli, F.

2015-01-01

Low-intensity lasers are used for prevention and management of oral mucositis induced by anticancer therapy, but the effectiveness of treatment depends on the genetic characteristics of affected cells. This study evaluated the survival and induction of filamentation of Escherichia coli cells deficient in the nucleotide excision repair pathway, and the action of T 4 endonuclease V on plasmid DNA exposed to low-intensity red and near-infrared laser light. Cultures of wild-type (strain AB1157) E. coli and strain AB1886 (deficient in uvrA protein) were exposed to red (660 nm) and infrared (808 nm) lasers at various fluences, powers and emission modes to study bacterial survival and filamentation. Also, plasmid DNA was exposed to laser light to study DNA lesions produced in vitro by T 4 endonuclease V. Low-intensity lasers: i) had no effect on survival of wild-type E. coli but decreased the survival of uvrA protein-deficient cells, ii) induced bacterial filamentation, iii) did not alter the electrophoretic profile of plasmids in agarose gels, and iv) did not alter the electrophoretic profile of plasmids incubated with T 4 endonuclease V. These results increase our understanding of the effects of laser light on cells with various genetic characteristics, such as xeroderma pigmentosum cells deficient in nucleotide excision pathway activity in patients with mucositis treated by low-intensity lasers. (author)

Nucleotide excision repair pathway assessment in DNA exposed to low-intensity red and infrared lasers

Energy Technology Data Exchange (ETDEWEB)

Fonseca, A.S.; Campos, V.M.A.; Magalhaes, L.A.G., E-mail: adnfonseca@ig.com.br [Instituto de Biologia Roberto Alcantara Gomes, Rio de Janeiro, RJ (Brazil). Departamento de Biofisica e Biometria. Lab. de Ciencias Radiologicas; Paoli, F. [Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, MG (Brazil). Instituto de Ciencias Biologicas. Departamento de Morfologia

2015-10-15

Low-intensity lasers are used for prevention and management of oral mucositis induced by anticancer therapy, but the effectiveness of treatment depends on the genetic characteristics of affected cells. This study evaluated the survival and induction of filamentation of Escherichia coli cells deficient in the nucleotide excision repair pathway, and the action of T{sub 4} endonuclease V on plasmid DNA exposed to low-intensity red and near-infrared laser light. Cultures of wild-type (strain AB1157) E. coli and strain AB1886 (deficient in uvrA protein) were exposed to red (660 nm) and infrared (808 nm) lasers at various fluences, powers and emission modes to study bacterial survival and filamentation. Also, plasmid DNA was exposed to laser light to study DNA lesions produced in vitro by T{sub 4} endonuclease V. Low-intensity lasers: i) had no effect on survival of wild-type E. coli but decreased the survival of uvrA protein-deficient cells, ii) induced bacterial filamentation, iii) did not alter the electrophoretic profile of plasmids in agarose gels, and iv) did not alter the electrophoretic profile of plasmids incubated with T{sub 4} endonuclease V. These results increase our understanding of the effects of laser light on cells with various genetic characteristics, such as xeroderma pigmentosum cells deficient in nucleotide excision pathway activity in patients with mucositis treated by low-intensity lasers. (author)

Characterization of silicon microstrip sensors with a pulsed infrared laser system for the CBM experiment at FAIR

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Pradeep [Goethe Univ., Frankfurt (Germany); GSI (Germany); Eschke, Juergen [GSI (Germany); FAIR (Germany); Collaboration: CBM-Collaboration

2014-07-01

The Silicon Tracking System (STS) for the Compressed Baryonic Matter (CBM) experiment at FAIR will comprise more than 1200 double-sided silicon microstrip sensors. For the quality assurance of the prototype sensors a laser test system has been built up. The aim of the sensor scans with the pulsed infrared laser system is to determine the charge sharing between strips and to measure the uniformity of the sensor response over the whole active area. The laser system measures the sensor response in an automatized procedure at several thousand positions across the sensor with focused infrared laser light (σ∼15 μm, λ=1060 nm). The duration (5 ns) and power (few mW) of the laser pulses are selected such, that the absorption of the laser light in the 300 μm thick silicon sensors produces a number of about 24k electrons, which is similar to the charge created by minimum ionizing particles in these sensors. Results from the characterization of monolithic active pixel sensors, to understand the spot-size of the laser, and laser scans for different sensors are presented.

Investigation of SOI Raman Lasers for Mid-Infrared Gas Sensing

Science.gov (United States)

Passaro, Vittorio M.N.; De Leonardis, Francesco

2009-01-01

In this paper, the investigation and detailed modeling of a cascaded Raman laser, operating in the midwave infrared region, is described. The device is based on silicon-on-insulator optical waveguides and a coupled resonant microcavity. Theoretical results are compared with recent experiments, demonstrating a very good agreement. Design criteria are derived for cascaded Raman lasers working as continuous wave light sources to simultaneously sense two types of gases, namely C2H6 and CO2, at a moderate power level of 130 mW. PMID:22408481

Laser-induced filaments in the mid-infrared

International Nuclear Information System (INIS)

Zheltikov, A M

2017-01-01

Laser-induced filamentation in the mid-infrared gives rise to unique regimes of nonlinear wave dynamics and reveals in many ways unusual nonlinear-optical properties of materials in this frequency range. The λ 2 scaling of the self-focusing threshold P cr , with radiation wavelength λ , allows the laser powers transmitted by single mid-IR filaments to be drastically increased without the loss of beam continuity and spatial coherence. When extended to the mid-infrared, laser filamentation enables new methods of pulse compression. Often working around the universal physical limitations, it helps generate few-cycle and subcycle field waveforms within an extraordinarily broad range of peak powers, from just a few up to hundreds of P cr . As a part of a bigger picture, laser-induced filamentation in the mid-infrared offers important physical insights into the general properties of the nonlinear-optical response of matter as a function of the wavelength. Unlike their near-infrared counterparts, which can be accurately described within the framework of perturbative nonlinear optics, mid-infrared filaments often entangle perturbative and nonperturbative nonlinear-optical effects, showing clear signatures of strong-field optical physics. With the role of nonperturbative nonlinear-optical phenomena growing, as a general tendency, with the field intensity and the driver wavelength, extension of laser filamentation to even longer driver wavelengths, toward the long-wavelength infrared, promises a hic sunt dracones land. (topical review)

Method for measuring retardation of infrared wave-plate by modulated-polarized visible light

Science.gov (United States)

Zhang, Ying; Song, Feijun

2012-11-01

A new method for precisely measuring the optical phase retardation of wave-plates in the infrared spectral region is presented by using modulated-polarized visible light. An electro-optic modulator is used to accurately determine the zero point by the frequency-doubled signal of the Modulated-polarized light. A Babinet-Soleil compensator is employed to make the phase delay compensation. Based on this method, an instrument is set up to measure the retardations of the infrared wave-plates with visible region laser. Measurement results with high accuracy and sound repetition are obtained by simple calculation. Its measurement precision is less than and repetitive precision is within 0.3%.

Fabrication of Shatter-Proof Metal Hollow-Core Optical Fibers for Endoscopic Mid-Infrared Laser Applications

Directory of Open Access Journals (Sweden)

Katsumasa Iwai

2018-04-01

Full Text Available A method for fabricating robust and thin hollow-core optical fibers that carry mid-infrared light is proposed for use in endoscopic laser applications. The fiber is made of stainless steel tubing, eliminating the risk of scattering small glass fragments inside the body if the fiber breaks. To reduce the inner surface roughness of the tubing, a polymer base layer is formed prior to depositing silver and optical-polymer layers that confine light inside the hollow core. The surface roughness is greatly decreased by re-coating thin polymer base layers. Because of this smooth base layer surface, a uniform optical-polymer film can be formed around the core. As a result, clear interference peaks are observed in both the visible and mid-infrared regions. Transmission losses were also low for the carbon dioxide laser used for medical treatments as well as the visible laser diode used for an aiming beam. Measurements of bending losses for these lasers demonstrate the feasibility of the designed fiber for endoscopic applications.

Novel technique for manipulating MOX fuel particles using radiation pressure of a laser light

International Nuclear Information System (INIS)

Omori, R.; Suzuki, A.

2001-01-01

We proposed two principles based on the laser manipulation technique for collecting MOX fuel particles floating in air. While Principle A was based on the acceleration of the MOX particles due to the radiation pressure of a visible laser light, Principle B was based on the gradient forces exerted on the particles when an infrared laser light was incident. Principle A was experimentally verified using MnO 2 particles. Numerical results also showed the possibility of collecting MOX fuel particles based on both the principles. (authors)

Infrared laser spectroscopic trace gas sensing

Science.gov (United States)

Sigrist, Markus

2016-04-01

Chemical sensing and analyses of gas samples by laser spectroscopic methods are attractive owing to several advantages such as high sensitivity and specificity, large dynamic range, multi-component capability, and lack of pretreatment or preconcentration procedures. The preferred wavelength range comprises the fundamental molecular absorption range in the mid-infared between 3 and 15 μm, whereas the near-infrared range covers the (10-100 times weaker) higher harmonics and combination bands. The availability of near-infrared and, particularly, of broadly tunable mid-infrared sources like external cavity quantum cascade lasers (EC-QCLs), interband cascade lasers (ICLs), difference frequency generation (DFG), optical parametric oscillators (OPOs), recent developments of diode-pumped lead salt semiconductor lasers, of supercontinuum sources or of frequency combs have eased the implementation of laser-based sensing devices. Sensitive techniques for molecular absorption measurements include multipass absorption, various configurations of cavity-enhanced techniques such as cavity ringdown (CRD), or of photoacoustic spectroscopy (PAS) including quartz-enhanced (QEPAS) or cantilever-enhanced (CEPAS) techniques. The application requirements finally determine the optimum selection of laser source and detection scheme. In this tutorial talk I shall discuss the basic principles, present various experimental setups and illustrate the performance of selected systems for chemical sensing of selected key atmospheric species. Applications include an early example of continuous vehicle emission measurements with a mobile CO2-laser PAS system [1]. The fast analysis of C1-C4 alkanes at sub-ppm concentrations in gas mixtures is of great interest for the petrochemical industry and was recently achieved with a new type of mid-infrared diode-pumped piezoelectrically tuned lead salt vertical external cavity surface emitting laser (VECSEL) [2]. Another example concerns measurements on short

Photothermal effect of infrared lasers on ex vivo lamb brain tissues

Science.gov (United States)

Özgürün, Baturay; Gülsoy, Murat

2018-02-01

Here, the most suitable infrared laser for a neurosurgery operation is suggested, among 1940-nm thulium fiber, 1470-nm diode, 1070-nm ytterbium fiber and 980-nm diode lasers. Cortical and subcortical ex-vivo lamb brain tissues are exposed to the laser light with the combinations of some laser parameters such as output power, energy density, operation mode (continuous and pulsed-modulated) and operation time. In this way, the greatest ablation efficiency associated with the best neurosurgical laser type can be defined. The research can be divided into two parts; pre-dosimetry and dosimetry studies. The former is used to determine safe operation zones for the dosimetry study by defining coagulation and carbonization onset times for each of the brain tissues. The latter is the main part of this research, and both tissues are exposed to laser irradiation with various energy density levels associated with the output power and operation time. In addition, photo-thermal effects are compared for two laser operation modes, and then coagulation and ablation diameters to calculate the ablation efficiency are measured under a light microscope. Consequently, results are compared graphically and statistically, and it is found that thulium and 1470-nm diode lasers can be utilized as subcortical and cortical tissue ablator devices, respectively.

Dispersion of near-infrared laser energy through radicular dentine when using plain or conical tips.

Science.gov (United States)

Teo, Christine Yi Jia; George, Roy; Walsh, Laurence J

2018-02-01

The aim of this study was to investigate the influence of tip design on patterns of laser energy dispersion through the dentine of tooth roots when using near-infrared diode lasers. Diode laser emissions of 810 or 940 nm were used in combination with optical fiber tips with either conventional plain ends or conical ends, to irradiate tooth roots of oval or round cross-sectional shapes. The lasers were operated in continuous wave mode at 0.5 W for 5 s with the distal end of the fiber tip placed in the apical or coronal third of the root canal at preset positions. Laser light exiting through the roots and apical foramen was imaged, and the extent of lateral spread calculated. There was a significant difference in infrared light exiting the root canal apex between plain and conical fiber tips for both laser wavelengths, with more forward transmission of laser energy through the apex for plain tips. For both laser wavelengths, there were no significant differences in emission patterns when the variable of canal shape was used and all other variables were kept the same (plain vs conical tip, tip position). To ensure optimal treatment effect and to prevent the risks of inadvertent laser effects on the adjacent periapical tissues, it is important to have a good understanding of laser transmission characteristics of the root canal and root dentine. Importantly, it is also essential to understand transmission characteristics of plain and conical fibers tips.

Diagnostic studies of molecular plasmas using mid-infrared semiconductor lasers

NARCIS (Netherlands)

Röpcke, J.; Welzel, S.; Lang, N.; Hempel, F.; Gatilova, L.; Guaitella, O.; Rousseau, A.; Davies, P.B.

2008-01-01

Within the last decade mid-infrared absorption spectroscopy between 3 and 20 µm, known as infrared laser absorption spectroscopy (IRLAS) and based on tuneable semiconductor lasers, namely lead salt diode lasers, often called tuneable diode lasers (TDL), and quantum cascade lasers (QCL) has

Analysis of peripheral thermal damage after laser irradiation of dentin using polarized light microscopy and synchrotron radiation infrared spectromicroscopy

Science.gov (United States)

Dela Rosa, Alfredo; Sarma, Anupama V.; Le, Charles Q.; Jones, Robert S.; Fried, Daniel

2004-05-01

It is necessary to minimize peripheral thermal damage during laser irradiation, since thermal damage to collagen and mineral compromises the bond strength to restorative materials in dentin and inhibits healing and osteointegration in bone. The overall objective of this study was to test the hypothesis that lasers resonant to the specific absorption of water, collagen, and hydroxyapatite with pulse durations less than the thermal relaxation times at each respective laser wavelength will efficiently remove dentin with minimal peripheral thermal damage. Precise incisions were produced in 3 x 3 mm2 blocks of human dentin using CO2 (9.6 μm), Er:YSGG (2.79 μm), and Nd:YAG (355 nm) lasers with and without a computer controlled water spray. Polarization-sensitive optical coherence tomography was used to obtain optical cross-sections of each incision to determine the rate and efficiency of ablation. The peripheral thermal damage zone around each incision was analyzed using polarized light microscopy (PLM) and Synchrotron-Radiation Fourier Transform Infrared Spectro-microscopy (SR-FTIR). Thermally induced chemical changes to both mineral and the collagen matrix was observed with SR-FTIR with a 10-μm spatial resolution and those changes were correlated with optical changes observed with PLM. Minimal (alveolar bone.

Resonant infrared laser deposition of polymer-nanocomposite materials for optoelectronic applications

Science.gov (United States)

Park, Hee K.; Schriver, Kenneth E.; Haglund, Richard F.

2011-11-01

Polymers find a number of potentially useful applications in optoelectronic devices. These include both active layers, such as light-emitting polymers and hole-transport layers, and passive layers, such as polymer barrier coatings and light-management films. This paper reports the experimental results for polymer films deposited by resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) and resonant infrared pulsed laser deposition (RIR-PLD) for commercial optoelectronic device applications. In particular, light-management films, such as anti-reflection coatings, require refractive-index engineering of a material. However, refractive indices of polymers fall within a relatively narrow range, leading to major efforts to develop both low- and high-refractive-index polymers. Polymer nanocomposites can expand the range of refractive indices by incorporating low- or high-refractive-index nanoscale materials. RIR-MAPLE is an excellent technique for depositing polymer-nanocomposite films in multilayer structures, which are essential to light-management coatings. In this paper, we report our efforts to engineer the refractive index of a barrier polymer by combining RIR-MAPLE of nanomaterials (for example, high refractive-index TiO2 nanoparticles) and RIR-PLD of host polymer. In addition, we report on the properties of organic and polymer films deposited by RIR-MAPLE and/or RIR-PLD, such as Alq3 [tris(8-hydroxyquinoline) aluminum] and PEDOT:PSS [poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)]. Finally, the challenges and potential for commercializing RIR-MAPLE/PLD, such as industrial scale-up issues, are discussed.

A Tunable Mid-Infrared Solid-State Laser with a Compact Thermal Control System

Directory of Open Access Journals (Sweden)

Deyang Yu

2018-05-01

Full Text Available Tunable mid-infrared lasers are widely used in laser spectroscopy, gas sensing and many other related areas. In order to solve heat dissipation problems and improve the environmental temperature adaptability of solid-state laser sources, a tunable all-fiber laser pumped optical parametric oscillator (OPO was established, and a compact thermal control system based on thermoelectric coolers, an automatic temperature control circuit, cooling fins, fans and heat pipes was integrated and designed for the laser. This system is compact, light and air-cooling which satisfies the demand for miniaturization of lasers. A mathematical model and method was established to estimate the cooling capacity of this thermal control system under different ambient environments. A finite-element model was built and simulated to analyze the thermal transfer process. Experiments in room and high temperature environments were carried out and showed that the substrate temperature of a pump module could be maintained at a stable value with controlled precision to 0.2 degrees, while the output power stability of the laser was within ±1%. The experimental results indicate that this compact air-cooling thermal control system could effectively solve the heat dissipation problem of mid-infrared solid-state lasers with a one hundred watts level pump module in room and high temperature environments.

Non-invasive characterization and quality assurance of silicon micro-strip detectors using pulsed infrared laser

Science.gov (United States)

Ghosh, P.

2016-01-01

The Compressed Baryonic Matter (CBM) experiment at FAIR is composed of 8 tracking stations consisting of roughly 1300 double sided silicon micro-strip detectors of 3 different dimensions. For the quality assurance of prototype micro-strip detectors a non-invasive detector charaterization is developed. The test system is using a pulsed infrared laser for charge injection and characterization, called Laser Test System (LTS). The system is aimed to develop a set of characterization procedures which are non-invasive (non-destructive) in nature and could be used for quality assurances of several silicon micro-strip detectors in an efficient, reliable and reproducible way. The procedures developed (as reported here) uses the LTS to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. The prototype detector modules which are tested with the LTS so far have 1024 strips with a pitch of 58 μm on each side. They are read-out using a self-triggering prototype read-out electronic ASIC called n-XYTER. The LTS is designed to measure sensor response in an automatized procedure at several thousand positions across the sensor with focused infra-red laser light (spot size ≈ 12 μm, wavelength = 1060 nm). The pulse with a duration of ≈ 10 ns and power ≈ 5 mW of the laser pulse is selected such, that the absorption of the laser light in the 300 μm thick silicon sensor produces ≈ 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. The laser scans different prototype sensors and various non-invasive techniques to determine characteristics of the detector modules for the quality assurance is reported.

Tritium removal from contaminated water via infrared laser multiple-photon dissociation

International Nuclear Information System (INIS)

Maienschein, J.L.; Magnotta, F.; Herman, I.P.; Aldridge, F.T.; Hsiao, P.

1983-01-01

Isotope separation by means of infrared-laser multiple-photon dissociation offers an efficient way to recover tritium from contaminated light or heavy water found in fission and fusion reactors. For tritium recovery from heavy water, chemical exchange of tritium into deuterated chloroform is followed by selective laser dissociation of tritiated chloroform and removal of the tritiated photoproduct, TCl. The single-step separation factor is at least 2700 and is probably greater than 5000. Here we present a description of the tritium recovery process, along with recent accomplishments in photochemical studies and engineering analysis of a recovery system

Compact RGBY light sources with high luminance for laser display applications

Science.gov (United States)

Paschke, Katrin; Blume, Gunnar; Werner, Nils; Müller, André; Sumpf, Bernd; Pohl, Johannes; Feise, David; Ressel, Peter; Sahm, Alexander; Bege, Roland; Hofmann, Julian; Jedrzejczyk, Daniel; Tränkle, Günther

2018-02-01

Watt-class visible laser light with a high luminance can be created with high-power GaAs-based lasers either directly in the red spectral region or using single-pass second harmonic generation (SHG) for the colors in the blue-yellow spectral region. The concepts and results of red- and near infrared-emitting distributed Bragg reflector tapered lasers and master oscillator power amplifier systems as well as their application for SHG bench-top experiments and miniaturized modules are presented. Examples of these high-luminance light sources aiming at different applications such as flying spot display or holographic 3D cinema are discussed in more detail. The semiconductor material allows an easy adaptation of the wavelength allowing techniques such as six-primary color 3D projection or color space enhancement by adding a fourth yellow color.

Infrared light sensor applied to early detection of tooth decay

Science.gov (United States)

Benjumea, Eberto; Espitia, José; Díaz, Leonardo; Torres, Cesar

2017-08-01

The approach dentistry to dental care is gradually shifting to a model focused on early detection and oral-disease prevention; one of the most important methods of prevention of tooth decay is opportune diagnosis of decay and reconstruction. The present study aimed to introduce a procedure for early diagnosis of tooth decay and to compare result of experiment of this method with other common treatments. In this setup, a laser emitting infrared light is injected in core of one bifurcated fiber-optic and conduced to tooth surface and with the same bifurcated fiber the radiation reflected for the same tooth is collected and them conduced to surface of sensor that measures thermal and light frequencies to detect early signs of decay below a tooth surface, where demineralization is difficult to spot with x-ray technology. This device will can be used to diagnose tooth decay without any chemicals and rays such as high power lasers or X-rays.

Lethal photosensitization of wound-associated microbes using indocyanine green and near-infrared light

Directory of Open Access Journals (Sweden)

Wilson Michael

2008-07-01

Full Text Available Abstract Background The increase in resistance to antibiotics among disease-causing bacteria necessitates the development of alternative antimicrobial approaches such as the use of light-activated antimicrobial agents (LAAAs. Light of an appropriate wavelength activates the LAAA to produce cytotoxic species which can then cause bacterial cell death via loss of membrane integrity, lipid peroxidation, the inactivation of essential enzymes, and/or exertion of mutagenic effects due to DNA modification. In this study, the effect of the LAAA indocyanine green excited with high or low intensity light (808 nm from a near-infrared laser (NIR on the viability of Staphylococcus aureus, Streptococcus pyogenes and Pseudomonas aeruginosa was investigated. Results All species were susceptible to killing by the LAAA, the bactericidal effect being dependent on both the concentration of indocyanine green and the light dose. Indocyanine green photosensitization using both high (1.37 W cm-2 and low (0.048 W cm-2 intensity NIR laser light was able to achieve reductions of 5.6 log10 (>99.99% and 6.8 log10 (>99.99% in the viable counts of Staph. aureus and Strep. pyogenes (using starting concentrations of 106–107 CFU ml-1. Kills of 99.99% were obtained for P. aeruginosa (initial concentration 108–109 CFU ml-1 photosensitized by the high intensity light (1.37 W cm-2; while a kill of 80% was achieved using low intensity irradiation (0.07 W cm-2. The effects of L-tryptophan (a singlet oxygen scavenger and deuterium oxide (as an enhancer of the life span of singlet oxygen on the survival of Staph. aureus was also studied. L-tryptophan reduced the proportion of Staph. aureus killed; whereas deuterium oxide increased the proportion killed suggesting that singlet oxygen was involved in the killing of the bacteria. Conclusion These findings imply that indocyanine green in combination with light from a near-infrared laser may be an effective means of eradicating bacteria

Present status of the development of far-infrared coherent light sources with the ISIR linear accelerator

Energy Technology Data Exchange (ETDEWEB)

Okuda, Shuichi [Osaka Univ., Ibaraki (Japan). Inst. of Scientific and Industrial Research

1996-07-01

Far-infrared light sources are being developed with a 38-MeV L-band linear accelerator at the Institute of Scientific and Industrial Research, Osaka University. In the experiments of free-electron laser the self-amplified spontaneous emission was observed at wavelengths of 20 and 40 {mu}m with a high-intensity single-bunch beam for a single passage through a wiggler. In the free-electron laser oscillation experiments with a multibunch beam laser light was obtained at wavelengths from 32 to 40 {mu}m. The peak power in a micropulse of the laser was estimated to be 8.3 MW at a wavelength of 40 {mu}m. Coherent radiation emitted from bunched electrons was observed for Cherenkov and transition radiation processes with the single-bunch beam. (author)

Effects of Near-Infrared Laser on Neural Cell Activity

International Nuclear Information System (INIS)

Mochizuki-Oda, Noriko; Kataoka, Yosky; Yamada, Hisao; Awazu, Kunio

2004-01-01

Near-infrared laser has been used to relieve patients from various kinds of pain caused by postherpetic neuralgesia, myofascial dysfunction, surgical and traumatic wound, cancer, and rheumatoid arthritis. Clinically, He-Ne (λ=632.8 nm, 780 nm) and Ga-Al-As (805 ± 25 nm) lasers are used to irradiate trigger points or nerve ganglion. However the precise mechanisms of such biological actions of the laser have not yet been resolved. Since laser therapy is often effective to suppress the pain caused by hyperactive excitation of sensory neurons, interactions with laser light and neural cells are suggested. As neural excitation requires large amount of energy liberated from adenosine triphosphate (ATP), we examined the effect of 830-nm laser irradiation on the energy metabolism of the rat central nervous system and isolated mitochondria from brain. The diode laser was applied for 15 min with irradiance of 4.8 W/cm2 on a 2 mm-diameter spot at the brain surface. Tissue ATP content of the irradiated area in the cerebral cortex was 19% higher than that of the non-treated area (opposite side of the cortex), whereas the ADP content showed no significant difference. Irradiation at another wavelength (652 nm) had no effect on either ATP or ADP contents. The temperature of the brain tissue was increased 4.5-5.0 deg. C during the irradiation of both 830-nm and 652-nm laser light. Direct irradiation of the mitochondrial suspension did not show any wavelength-dependent acceleration of respiration rate nor ATP synthesis. These results suggest that the increase in tissue ATP content did not result from the thermal effect, but from specific effect of the laser operated at 830 nm. Electrophysiological studies showed the hyperpolarization of membrane potential of isolated neurons and decrease in membrane resistance with irradiation of the laser, suggesting an activation of potassium channels. Intracellular ATP is reported to regulate some kinds of potassium channels. Possible mechanisms

New gonioscopy system using only infrared light.

Science.gov (United States)

Sugimoto, Kota; Ito, Kunio; Matsunaga, Koichi; Miura, Katsuya; Esaki, Koji; Uji, Yukitaka

2005-08-01

To describe an infrared gonioscopy system designed to observe the anterior chamber angle under natural mydriasis in a completely darkened room. An infrared light filter was used to modify the light source of the slit-lamp microscope. A television monitor connected to a CCD monochrome camera was used to indirectly observe the angle. Use of the infrared system enabled observation of the angle under natural mydriasis in a completely darkened room. Infrared gonioscopy is a useful procedure for the observation of the angle under natural mydriasis.

Broadband integrated mid infrared light sources as enabling technology for point of care mid-infrared spectroscopy

Science.gov (United States)

2017-08-20

AFRL-AFOSR-JP-TR-2017-0061 Broadband integrated mid-infrared light sources as enabling technology for point-of-care mid- infrared spectroscopy Alex...mid-infrared light sources as enabling technology for point-of-care mid-infrared spectroscopy 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-16-1-4037...Broadband integrated mid-infrared light sources as enabling technology for point-of-care mid- infrared spectroscopy ” Date: 16th August 2017 Name

The protozoan, Paramecium primaurelia, as a non-sentient model to test laser light irradiation: The effects of an 808nm infrared laser diode on cellular respiration.

Science.gov (United States)

Amaroli, Andrea; Ravera, Silvia; Parker, Steven; Panfoli, Isabella; Benedicenti, Alberico; Benedicenti, Stefano

2015-07-01

Photobiomodulation (PBM) has been used in clinical practice for more than 40 years. Unfortunately, conflicting literature has led to the labelling of PBM as a complementary or alternative medicine approach. However, past and ongoing clinical and research studies by reputable investigators have re-established the merits of PBM as a genuine medical therapy, and the technique has, in the last decade, seen an exponential increase in the numbers of clinical instruments available, and their applications. This resurgence has led to a clear need for appropriate experimental models to test the burgeoning laser technology being developed for medical applications. In this context, an ethical model that employs the protozoan, Paramecium primaurelia, is proposed. We studied the possibility of using the measure of oxygen consumption to test PBM by irradiation with an infrared or near-infrared laser. The results show that an 808nm infrared laser diode (1W; 64J/cm²) affects cellular respiration in P. primaurelia, inducing, in the irradiated cells, a significantly (p Paramecium can be an excellent tool in biological assays involving infrared and near-infrared PBM, as it combines the advantages of in vivo results with the practicality of in vitro testing. This test represents a fast, inexpensive and straightforward assay, which offers an alternative to both traditional in vivo testing and more expensive mammalian cellular cultures. 2015 FRAME.

Corneal tissue welding with infrared laser irradiation after clear corneal incision.

Science.gov (United States)

Rasier, Rfat; Ozeren, Mediha; Artunay, Ozgür; Bahçecioğlu, Halil; Seçkin, Ismail; Kalaycoğlu, Hamit; Kurt, Adnan; Sennaroğlu, Alphan; Gülsoy, Murat

2010-09-01

The aim of this study was to investigate the potential of infrared lasers for corneal welding to seal corneal cuts done in an experimental animal model. Full-thickness corneal cuts on freshly enucleated bovine eyes were irradiated with infrared (809-nm diode, 980-nm diode, 1070-nm YLF, and 1980-nm Tm:YAP) lasers to get immediate laser welding. An 809-nm laser was used with the topical application of indocyanine green to enhance the photothermal interaction at the weld site. In total, 60 bovine eyes were used in this study; 40 eyes were used in the first part of the study for the determination of optimal welding parameters (15 eyes were excluded because of macroscopic carbonization, opacification, or corneal shrinkage; 2 eyes were used for control), and 20 eyes were used for further investigation of more promising lasers (YLF and Tm:YAP). Laser wavelength, irradiating power, exposure time, and spot size were the dose parameters, and optimal dose for immediate closure with minimal thermal damage was estimated through histological examination of welded samples. In the first part of the study, results showed that none of the applications was satisfactory. Full-thickness success rates were 28% (2 of 7) for 809-nm and for 980-nm diode lasers and 67% (2 of 3) for 1070-nm YLF and (4 of 6) for 1980-nm Tm:YAP lasers. In the second part of the study, YLF and Tm:YAP lasers were investigated with bigger sample size. Results were not conclusive but promising again. Five corneal incisions were full-thickness welded out of 10 corneas with 1070-nm laser, and 4 corneal incisions were partially welded out of 10 corneas with 1980-nm laser in the second part of the study. Results showed that noteworthy corneal welding could be obtained with 1070-nm YLF laser and 1980-nm Tm:YAP laser wavelengths. Furthermore, in vitro and in vivo studies will shed light on the potential usage of corneal laser welding technique.

Silicon isotope separation utilizing infrared multiphoton dissociation of Si2F6 irradiated with two-color CO2 laser light

International Nuclear Information System (INIS)

Yokoyama, Atsushi; Ohba, Hironori; Hashimoto, Masashi; Arai, Shigeyoshi

2002-01-01

Silicon isotope separation has been done by utilizing the Infrared Multiphoton Dissociation (IRMPD) of Si 2 F 6 irradiated with two-color CO 2 laser lights. The two-color excitation method improved the separation efficiency keeping the high enrichment factors. For example, 99.74% of 28 Si was obtained at 49.63% dissociation of Si 2 F 6 after the simultaneous irradiation of 200 pulses with 966.23 cm -1 photons (0.084 J/cm 2 ) and 954.55 cm -1 photons (0.658 J/cm 2 ), while 2000 pulses were needed to obtain 99.35% of 28 Si at 35.6% dissociation in the case of only one-color irradiation at 954.55 cm -1 (0.97 J/cm 2 ). (author)

Quantum optical signatures in strong-field laser physics: Infrared photon counting in high-order-harmonic generation.

Science.gov (United States)

Gonoskov, I A; Tsatrafyllis, N; Kominis, I K; Tzallas, P

2016-09-07

We analytically describe the strong-field light-electron interaction using a quantized coherent laser state with arbitrary photon number. We obtain a light-electron wave function which is a closed-form solution of the time-dependent Schrödinger equation (TDSE). This wave function provides information about the quantum optical features of the interaction not accessible by semi-classical theories. With this approach we can reveal the quantum optical properties of high harmonic generation (HHG) process in gases by measuring the photon statistics of the transmitted infrared (IR) laser radiation. This work can lead to novel experiments in high-resolution spectroscopy in extreme-ultraviolet (XUV) and attosecond science without the need to measure the XUV light, while it can pave the way for the development of intense non-classical light sources.

A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

Energy Technology Data Exchange (ETDEWEB)

Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner, E-mail: maentele@biophysik.uni-frankfurt.de [Institut für Biophysik, Goethe-Universität Frankfurt am Main, Max-von Laue-Straße 1, D-60438 Frankfurt am Main (Germany)

2014-08-15

A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

Science.gov (United States)

Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner

2014-08-01

A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

Generation of pulsed far-infrared radiation and its application for far-infrared time-resolved spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kondo, Yasuhiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

1996-07-01

So-called time-resolved spectroscopy technique has been used from old time as the means for studying the dynamic optical property, light-induced reaction and so on of matters. As an example, there is the method called pump and probe, and here, the wavelength of this probe light is the problem. If the object energy region is limited to about 0.1 eV, fast time-resolved spectroscopy is feasible relatively easily. However, energy region is extended to low energy region, the light source which is available as the pulsed probe light having sufficient intensity is limited. In this paper, the attempt of time-resolved spectroscopy utilizing coherent radiation, which has ended in failure, and the laser pulse-induced far-infrared radiation which can be utilized as new far-infrared probe light are reported. The reason why far-infrared radiation is used is explained. The attempt of time-resolved spectroscopy using NaCl crystals is reported on the equipment, the method of measuring absorption spectra and the results. Laser pulse-induced far-infrared radiation and the method of generating it are described. The multi-channel detector for far-infrared radiation which was made for trial is shown. (K.I.)

1.9 W yellow, CW, high-brightness light from a high efficiency semiconductor laser-based system

Science.gov (United States)

Hansen, A. K.; Christensen, M.; Noordegraaf, D.; Heist, P.; Papastathopoulos, E.; Loyo-Maldonado, V.; Jensen, O. B.; Stock, M. L.; Skovgaard, P. M. W.

2017-02-01

Semiconductor lasers are ideal sources for efficient electrical-to-optical power conversion and for many applications where their small size and potential for low cost are required to meet market demands. Yellow lasers find use in a variety of bio-related applications, such as photocoagulation, imaging, flow cytometry, and cancer treatment. However, direct generation of yellow light from semiconductors with sufficient beam quality and power has so far eluded researchers. Meanwhile, tapered semiconductor lasers at near-infrared wavelengths have recently become able to provide neardiffraction- limited, single frequency operation with output powers up to 8 W near 1120 nm. We present a 1.9 W single frequency laser system at 562 nm, based on single pass cascaded frequency doubling of such a tapered laser diode. The laser diode is a monolithic device consisting of two sections: a ridge waveguide with a distributed Bragg reflector, and a tapered amplifier. Using single-pass cascaded frequency doubling in two periodically poled lithium niobate crystals, 1.93 W of diffraction-limited light at 562 nm is generated from 5.8 W continuous-wave infrared light. When turned on from cold, the laser system reaches full power in just 60 seconds. An advantage of using a single pass configuration, rather than an external cavity configuration, is increased stability towards external perturbations. For example, stability to fluctuating case temperature over a 30 K temperature span has been demonstrated. The combination of high stability, compactness and watt-level power range means this technology is of great interest for a wide range of biological and biomedical applications.

Near-infrared light-responsive liposomal contrast agent for photoacoustic imaging and drug release applications.

Science.gov (United States)

Sivasubramanian, Kathyayini; Mathiyazhakan, Malathi; Wiraja, Christian; Upputuri, Paul Kumar; Xu, Chenjie; Pramanik, Manojit

2017-04-01

Photoacoustic imaging has become an emerging tool for theranostic applications. Not only does it help in release and therapeutic applications. We explore near-infrared light-sensitive liposomes coated with gold nanostars (AuNSs) for both imaging and drug release applications using a photoacoustic imaging system. Being amphiphilic, the liposomes lipid bilayer and the aqueous core enable encapsulation of both hydrophobic and hydrophilic drugs. The AuNSs on the surface of the liposomes act as photon absorbers due to their intrinsic surface plasmon resonance. Upon excitation by laser light at specific wavelength, AuNSs facilitate rapid release of the contents encapsulated in the liposomes due to local heating and pressure wave formation (photoacoustic wave). Herein, we describe the design and optimization of the AuNSs-coated liposomes and demonstrate the release of both hydrophobic and hydrophilic model drugs (paclitaxel and calcein, respectively) through laser excitation at near-infrared wavelength. The use of AuNSs-coated liposomes as contrast agents for photoacoustic imaging is also explored with tissue phantom experiments. In comparison to blood, the AuNSs-coated liposomes have better contrast (approximately two times) at 2-cm imaging depth.

Near infrared spectral imaging of explosives using a tunable laser source

Energy Technology Data Exchange (ETDEWEB)

Klunder, G L; Margalith, E; Nguyen, L K

2010-03-26

Diffuse reflectance near infrared hyperspectral imaging is an important analytical tool for a wide variety of industries, including agriculture consumer products, chemical and pharmaceutical development and production. Using this technique as a method for the standoff detection of explosive particles is presented and discussed. The detection of the particles is based on the diffuse reflectance of light from the particle in the near infrared wavelength range where CH, NH, OH vibrational overtones and combination bands are prominent. The imaging system is a NIR focal plane array camera with a tunable OPO/laser system as the illumination source. The OPO is programmed to scan over a wide spectral range in the NIR and the camera is synchronized to record the light reflected from the target for each wavelength. The spectral resolution of this system is significantly higher than that of hyperspectral systems that incorporate filters or dispersive elements. The data acquisition is very fast and the entire hyperspectral cube can be collected in seconds. A comparison of data collected with the OPO system to data obtained with a broadband light source with LCTF filters is presented.

Infrared laser diagnostics for ITER

International Nuclear Information System (INIS)

Hutchinson, D.P.; Richards, R.K.; Ma, C.H.

1995-01-01

Two infrared laser-based diagnostics are under development at ORNL for measurements on burning plasmas such as ITER. The primary effort is the development of a CO 2 laser Thomson scattering diagnostic for the measurement of the velocity distribution of confined fusion-product alpha particles. Key components of the system include a high-power, single-mode CO 2 pulsed laser, an efficient optics system for beam transport and a multichannel low-noise infrared heterodyne receiver. A successful proof-of-principle experiment has been performed on the Advanced Toroidal Facility (ATF) stellerator at ORNL utilizing scattering from electron plasma frequency satellites. The diagnostic system is currently being installed on Alcator C-Mod at MIT for measurements of the fast ion tail produced by ICRH heating. A second diagnostic under development at ORNL is an infrared polarimeter for Faraday rotation measurements in future fusion experiments. A preliminary feasibility study of a CO 2 laser tangential viewing polarimeter for measuring electron density profiles in ITER has been completed. For ITER plasma parameters and a polarimeter wavelength of 10.6 microm, a Faraday rotation of up to 26 degree is predicted. An electro-optic polarization modulation technique has been developed at ORNL. Laboratory tests of this polarimeter demonstrated a sensitivity of ≤ 0.01 degree. Because of the similarity in the expected Faraday rotation in ITER and Alcator C-Mod, a collaboration between ORNL and the MIT Plasma Fusion Center has been undertaken to test this polarimeter system on Alcator C-Mod. A 10.6 microm polarimeter for this measurement has been constructed and integrated into the existing C-Mod multichannel two-color interferometer. With present experimental parameters for C-Mod, the predicted Faraday rotation was on the order of 0.1 degree. Significant output signals were observed during preliminary tests. Further experiment and detailed analyses are under way

Differences between wavefront and subjective refraction for infrared light.

Science.gov (United States)

Teel, Danielle F W; Jacobs, Robert J; Copland, James; Neal, Daniel R; Thibos, Larry N

2014-10-01

To determine the accuracy of objective wavefront refractions for predicting subjective refractions for monochromatic infrared light. Objective refractions were obtained with a commercial wavefront aberrometer (COAS, Wavefront Sciences). Subjective refractions were obtained for 30 subjects with a speckle optometer validated against objective Zernike wavefront refractions on a physical model eye (Teel et al., Design and validation of an infrared Badal optometer for laser speckle, Optom Vis Sci 2008;85:834-42). Both instruments used near-infrared (NIR) radiation (835 nm for COAS, 820 nm for the speckle optometer) to avoid correction for ocular chromatic aberration. A 3-mm artificial pupil was used to reduce complications attributed to higher-order ocular aberrations. For comparison with paraxial (Seidel) and minimum root-mean-square (Zernike) wavefront refractions, objective refractions were also determined for a battery of 29 image quality metrics by computing the correcting lens that optimizes retinal image quality. Objective Zernike refractions were more myopic than subjective refractions for 29 of 30 subjects. The population mean discrepancy was -0.26 diopters (D) (SEM = 0.03 D). Paraxial (Seidel) objective refractions tended to be hyperopically biased (mean discrepancy = +0.20 D, SEM = 0.06 D). Refractions based on retinal image quality were myopically biased for 28 of 29 metrics. The mean bias across all 31 measures was -0.24 D (SEM = 0.03). Myopic bias of objective refractions was greater for eyes with brown irises compared with eyes with blue irises. Our experimental results are consistent with the hypothesis that reflected NIR light captured by the aberrometer originates from scattering sources located posterior to the entrance apertures of cone photoreceptors, near the retinal pigment epithelium. The larger myopic bias for brown eyes suggests that a greater fraction of NIR light is reflected from choroidal melanin in brown eyes compared with blue eyes.

Paramecium: a promising non-animal bioassay to study the effect of 808 nm infrared diode laser photobiomodulation.

Science.gov (United States)

Amaroli, Andrea; Parker, Steven; Dorigo, Gianluca; Benedicenti, Alberico; Benedicenti, Stefano

2015-01-01

Photobiostimulation and photobiomodulation (PBM) are terms applied to the manipulation of cellular behavior using low intensity light sources, which works on the principle of inducing a biological response through energy transfer. The aim of this investigation was to identify a laboratory assay to test the effect of an infrared diode laser light (808 nm) on cell fission rate. Sixty cells of Paramecium primaurelia were divided in two groups of 30. The first group (test group) was irradiated, at a temperature of 24°C, for 50 sec by a 808 nm diode laser with a flat top handpiece [1 cm of spot diameter, 1 W in continuous wave (CW), 50 sec irradiation time, 64 J/cm(2) of fluence]. The second group (control group) received no laser irradiation. All cells were transferred onto a depression slide, fed, and incubated in a moist chamber at a temperature of 24°C. The cells were exposed and monitored for 10 consecutive fission rates. Changes in temperature and pH were also evaluated. The exposed cells had a fission rate rhythm faster than the control cells, showing a binary fission significantly (pParamecium's lettuce infusion medium were observed. The 808 nm infrared diode laser light, at the irradiation parameters used in our work, results in a precocious fission rate in P. primaurelia cells, probably through an increase in metabolic activity, secondary to an energy transfer.

Infrared reflectometry of skin: Analysis of backscattered light from different skin layers

Science.gov (United States)

Pleitez, Miguel A.; Hertzberg, Otto; Bauer, Alexander; Lieblein, Tobias; Glasmacher, Mathias; Tholl, Hans; Mäntele, Werner

2017-09-01

We have recently reported infrared spectroscopy of human skin in vivo using quantum cascade laser excitation and photoacoustic or photothermal detection for non-invasive glucose measurement . Here, we analyze the IR light diffusely reflected from skin layers for spectral contributions of glucose. Excitation of human skin by an external cavity tunable quantum cascade laser in the spectral region from 1000 to 1245 cm- 1, where glucose exhibits a fingerprint absorption, yields reflectance spectra with some contributions from glucose molecules. A simple three-layer model of skin was used to calculate the scattering intensities from the surface and from shallow and deeper layers using the Boltzmann radiation transfer equation. Backscattering of light at wavelengths around 10 μm from the living skin occurs mostly from the Stratum corneum top layers and the shallow layers of the living epidermis. The analysis of the polarization of the backscattered light confirms this calculation. Polarization is essentially unchanged; only a very small fraction (light is due to specular reflectance and to scattering from layers close to the surface. Diffusely reflected light from deeper layers undergoing one or more scattering processes would appear with significantly altered polarization. We thus conclude that a non-invasive glucose measurement based on backscattering of IR light from skin would have the drawback that only shallow layers containing some glucose at concentrations only weakly related to blood glucose are monitored.

Intense pulsed light, near infrared pulsed light, and fractional laser combination therapy for skin rejuvenation in Asian subjects: a prospective multi-center study in China.

Science.gov (United States)

Tao, Li; Wu, Jiaqiang; Qian, Hui; Lu, Zhong; Li, Yuanhong; Wang, Weizhen; Zhao, Xiaozhong; Tu, Ping; Yin, Rui; Xiang, Leihong

2015-09-01

Ablative skin rejuvenation therapies have limitations for Asian people, including post-inflammatory hyperpigmentation and long down time. Non-ablative lasers are safer but have limited efficacy. This study is to investigate the safety and efficacy of a combination therapy consisting of intense pulsed light (IPL), near infrared (NIR) light, and fractional erbium YAG (Er:YAG) laser for skin rejuvenation in Asian people. This study recruited 113 subjects from six sites in China. Subjects were randomly assigned to a full-face group, who received combination therapy, and split-face groups, in which one half of the face received combination therapy and the other half received IPL monotherapy. Each subject received five treatment sessions during a period of 90 days. Subjects were followed up at 1 and 3 months post last treatment. Three months after last treatment, the full-face group (n = 57) had a global improvement rate of 29 % and 29 % for wrinkles, 32 % for skin texture, 33 % for pigment spots, 28 % for pore size, respectively. For patients in the split-face groups (n = 54), monotherapy side had a global improvement rate of 23 % and 20 % for wrinkles, 27 % for skin texture, 25 % for pigment spots, 25 % for pore size, respectively. Both combination therapy and monotherapy resulted in significant improvements at the follow-up visits compared to baseline (P < 0.001). Combination therapy showed significantly greater improvements compared to monotherapy at two follow-up visits (P < 0.05). Combination therapy is a safe and more effective strategy than IPL monotherapy for skin rejuvenation in Asian people.

[Near infrared light irradiator using halogen lamp].

Science.gov (United States)

Ide, Yasuo

2012-07-01

The practical electric light bulb was invented by Thomas Alva Edison in 1879. Halogen lamp is the toughest and brightest electric light bulb. With light filter, it is used as a source of near infrared light. Super Lizer and Alphabeam are made as near infrared light irradiator using halogen lamp. The light emmited by Super Lizer is linear polarized near infrared light. The wave length is from 600 to 1,600 nm and strongest at about 1,000 nm. Concerning Super Lizer, there is evidence of analgesic effects and normalization of the sympathetic nervous system. Super Lizer has four types of probes. SG type is used for stellate ganglion irradiation. B type is used for narrow area irradiation. C and D types are for broad area irradiation. The output of Alphabeam is not polarized. The wave length is from 700 to 1,600 nm and the strongest length is about 1,000nm. Standard attachment is used for spot irradiation. Small attachment is used for stellate ganglion irradiation. Wide attachment is used for broad area irradiation. The effects of Alphabeam are thought to be similar to that of Super Lizer.

Photoacoustic-based detector for infrared laser spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Scholz, L.; Palzer, S., E-mail: stefan.palzer@imtek.uni-freiburg.de [Department of Microsystems Engineering-IMTEK, Laboratory for Gas Sensors, University of Freiburg, Georges-Köhler-Allee 102, Freiburg 79110 (Germany)

2016-07-25

In this contribution, we present an alternative detector technology for use in direct absorption spectroscopy setups. Instead of a semiconductor based detector, we use the photoacoustic effect to gauge the light intensity. To this end, the target gas species is hermetically sealed under excess pressure inside a miniature cell along with a MEMS microphone. Optical access to the cell is provided by a quartz window. The approach is particularly suitable for tunable diode laser spectroscopy in the mid-infrared range, where numerous molecules exhibit large absorption cross sections. Moreover, a frequency standard is integrated into the method since the number density and pressure inside the cell are constant. We demonstrate that the information extracted by our method is at least equivalent to that achieved using a semiconductor-based photon detector. As exemplary and highly relevant target gas, we have performed direct spectroscopy of methane at the R3-line of the 2v{sub 3} band at 6046.95 cm{sup −1} using both detector technologies in parallel. The results may be transferred to other infrared-active transitions without loss of generality.

Diatomic infrared gas-dynamic laser

International Nuclear Information System (INIS)

Mckenzie, R.L.

1971-01-01

A laser is provided which utilizes the infrared vibration rotation transitions of a diatomic gas such as carbon monoxide. The laser action is produced by an active diatomic gas such as carbon monoxide mixed with a vibrationally resonant pumping gas such as nitrogen. In addition, a noble gas such as argon may be employed as a third gas in the mixture. The gas mixture contains from 1 to 80 vol percent of the active gas based on the pumping gas, and the third gas, if used, can constitute up to 90 percent of the total gas volume. A number of significantly different wavelengths can be produced by the laser. A single laser may contain several optical resonators at different locations, so that the desired wave length can be selected at will

Characterization of silicon micro-strip sensors with a pulsed infra-red laser system for the CBM experiment at FAIR

International Nuclear Information System (INIS)

Ghosh, P.

2015-01-01

The Compressed Baryonic Matter (CBM) experiment at FAIR is composed of 8 tracking stations consisting of 1292 double sided silicon micro-strip sensors. For the quality assurance of produced prototype sensors a laser test system (LTS) has been developed. The aim of the LTS is to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. The prototype sensors which are tested with the LTS so far have 256 strips with a pitch of 50 μm on each side. They are read-out using a self-triggering prototype read-out electronic ASIC called n-XYTER. The LTS is designed to measure sensor response in an automatized procedure at several thousand positions across the sensor with focused infra-red laser light (spot size ≈ 12 μm , wavelength = 1060 nm). The pulse with duration (≈ 10 ns) and power (≈ 5 mW) of the laser pulses is selected such, that the absorption of the laser light in the 300 μm thick silicon sensors produces a number of about 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. Laser scans different prototype sensors is reported

Modeling of light absorption in tissue during infrared neural stimulation

Science.gov (United States)

Thompson, Alexander C.; Wade, Scott A.; Brown, William G. A.; Stoddart, Paul R.

2012-07-01

A Monte Carlo model has been developed to simulate light transport and absorption in neural tissue during infrared neural stimulation (INS). A range of fiber core sizes and numerical apertures are compared illustrating the advantages of using simulations when designing a light delivery system. A range of wavelengths, commonly used for INS, are also compared for stimulation of nerves in the cochlea, in terms of both the energy absorbed and the change in temperature due to a laser pulse. Modeling suggests that a fiber with core diameter of 200 μm and NA=0.22 is optimal for optical stimulation in the geometry used and that temperature rises in the spiral ganglion neurons are as low as 0.1°C. The results show a need for more careful experimentation to allow different proposed mechanisms of INS to be distinguished.

Transdermal thiol-acrylate polyethylene glycol hydrogel synthesis using near infrared light

Science.gov (United States)

Chung, Solchan; Lee, Hwangjae; Kim, Hyung-Seok; Kim, Min-Gon; Lee, Luke P.; Lee, Jae Young

2016-07-01

Light-induced polymerization has been widely applied for hydrogel synthesis, which conventionally involves the use of ultraviolet or visible light to activate a photoinitiator for polymerization. However, with these light sources, transdermal gelation is not efficient and feasible due to their substantial interactions with biological systems, and thus a high power is required. In this study, we used biocompatible and tissue-penetrating near infrared (NIR) light to remotely trigger a thiol-acrylate reaction for efficient in vivo gelation with good controllability. Our gelation system includes gold nanorods as a photothermal agent, a thermal initiator, diacrylate polyethylene glycol (PEG), and thiolated PEG. Irradiation with a low-power NIR laser (0.3 W cm-2) could induce gelation via a mixed-mode reaction with a small increase in temperature (~5 °C) under the optimized conditions. We also achieved successful transdermal gelation via the NIR-assisted photothermal thiol-acryl reactions. This new type of NIR-assisted thiol-acrylate polymerization provides new opportunities for in situ hydrogel formation for injectable hydrogels and delivery of drugs/cells for various biomedical applications.Light-induced polymerization has been widely applied for hydrogel synthesis, which conventionally involves the use of ultraviolet or visible light to activate a photoinitiator for polymerization. However, with these light sources, transdermal gelation is not efficient and feasible due to their substantial interactions with biological systems, and thus a high power is required. In this study, we used biocompatible and tissue-penetrating near infrared (NIR) light to remotely trigger a thiol-acrylate reaction for efficient in vivo gelation with good controllability. Our gelation system includes gold nanorods as a photothermal agent, a thermal initiator, diacrylate polyethylene glycol (PEG), and thiolated PEG. Irradiation with a low-power NIR laser (0.3 W cm-2) could induce gelation

Transient Infrared Measurement of Laser Absorption Properties of Porous Materials

Directory of Open Access Journals (Sweden)

Marynowicz Andrzej

2016-06-01

Full Text Available The infrared thermography measurements of porous building materials have become more frequent in recent years. Many accompanying techniques for the thermal field generation have been developed, including one based on laser radiation. This work presents a simple optimization technique for estimation of the laser beam absorption for selected porous building materials, namely clinker brick and cement mortar. The transient temperature measurements were performed with the use of infrared camera during laser-induced heating-up of the samples’ surfaces. As the results, the absorbed fractions of the incident laser beam together with its shape parameter are reported.

Transient Infrared Measurement of Laser Absorption Properties of Porous Materials

Science.gov (United States)

Marynowicz, Andrzej

2016-06-01

The infrared thermography measurements of porous building materials have become more frequent in recent years. Many accompanying techniques for the thermal field generation have been developed, including one based on laser radiation. This work presents a simple optimization technique for estimation of the laser beam absorption for selected porous building materials, namely clinker brick and cement mortar. The transient temperature measurements were performed with the use of infrared camera during laser-induced heating-up of the samples' surfaces. As the results, the absorbed fractions of the incident laser beam together with its shape parameter are reported.

Laser/Light Therapy for Birthmarks

Science.gov (United States)

... for Every Season How to Choose the Best Skin Care Products In This Section Dermatologic Surgery What is dermatologic ... for Every Season How to Choose the Best Skin Care Products Laser/Light Therapy for Birthmarks In laser/light ...

Cutting and skin-ablative properties of pulsed mid-infrared laser surgery.

Science.gov (United States)

Kaufmann, R; Hartmann, A; Hibst, R

1994-02-01

Pulsed mid-infrared lasers allow a precise removal of soft tissues with only minimal thermal damage. To study the potential dermatosurgical usefulness of currently available systems at different wavelengths (2010-nm Thulium:YAG laser, 2100-nm Holmium:YAG laser, 2790-nm Erbium:YSGG laser, and 2940-nm Erbium:YAG laser) in vivo on pig skin. Immediate effects and wound healing of superficial laser-abrasions and incisions were compared with those of identical control lesions produced by dermabrasion, scalpel incisions, or laser surgery performed by a 1060-nm Nd:YAG and a 1060-nm CO2 laser (continuous and superpulsed mode). Best efficiency and least thermal injury was found for the pulsed Erbium:YAG laser, leading to ablative and incisional lesions comparable to those obtained by dermabrasion or superficial scalpel incisions, respectively. In contrast to other mid-infrared lasers tested, the 2940-nm Erbium:YAG laser thus provides a potential instrument for future applications in skin surgery, especially when aiming at a careful ablative removal of delicate superficial lesions with maximum sparing of adjacent tissue structures. However, in the purely incisional application mode pulsed mid-infrared lasers, though of potential usefulness in microsurgical indications (eg, surgery of the cornea), do not offer a suggestive alternative to simple scalpel surgery of the skin.

Infrared-laser-based fundus angiography

Science.gov (United States)

Klingbeil, Ulrich; Canter, Joseph M.; Lesiecki, Michael L.; Reichel, Elias

1994-06-01

Infrared fundus angiography, using the fluorescent dye indocyanine green (ICG), has shown great potential in delineating choroidal neovascularization (CNV) otherwise not detectable. A digital retinal imaging system containing a diode laser for illumination has been developed and optimized to perform high sensitivity ICG angiography. The system requires less power and generates less pseudo-fluorescence background than nonlaser devices. During clinical evaluation at three retinal centers more than 200 patients, the majority of which had age-related macular degeneration, were analyzed. Laser based ICG angiography was successful in outlining many of the ill-defined or obscure CNV as defined by fluorescein angiography. The procedure was not as successful with classic CNV. ICG angiograms were used to prepare and guide laser treatment.

Heuristic modelling of laser written mid-infrared LiNbO3 stressed-cladding waveguides.

Science.gov (United States)

Nguyen, Huu-Dat; Ródenas, Airán; Vázquez de Aldana, Javier R; Martínez, Javier; Chen, Feng; Aguiló, Magdalena; Pujol, Maria Cinta; Díaz, Francesc

2016-04-04

Mid-infrared lithium niobate cladding waveguides have great potential in low-loss on-chip non-linear optical instruments such as mid-infrared spectrometers and frequency converters, but their three-dimensional femtosecond-laser fabrication is currently not well understood due to the complex interplay between achievable depressed index values and the stress-optic refractive index changes arising as a function of both laser fabrication parameters, and cladding arrangement. Moreover, both the stress-field anisotropy and the asymmetric shape of low-index tracks yield highly birefringent waveguides not useful for most applications where controlling and manipulating the polarization state of a light beam is crucial. To achieve true high performance devices a fundamental understanding on how these waveguides behave and how they can be ultimately optimized is required. In this work we employ a heuristic modelling approach based on the use of standard optical characterization data along with standard computational numerical methods to obtain a satisfactory approximate solution to the problem of designing realistic laser-written circuit building-blocks, such as straight waveguides, bends and evanescent splitters. We infer basic waveguide design parameters such as the complex index of refraction of laser-written tracks at 3.68 µm mid-infrared wavelengths, as well as the cross-sectional stress-optic index maps, obtaining an overall waveguide simulation that closely matches the measured mid-infrared waveguide properties in terms of anisotropy, mode field distributions and propagation losses. We then explore experimentally feasible waveguide designs in the search of a single-mode low-loss behaviour for both ordinary and extraordinary polarizations. We evaluate the overall losses of s-bend components unveiling the expected radiation bend losses of this type of waveguides, and finally showcase a prototype design of a low-loss evanescent splitter. Developing a realistic waveguide

Transcranial red and near infrared light transmission in a cadaveric model.

Directory of Open Access Journals (Sweden)

Jared R Jagdeo

Full Text Available BACKGROUND AND OBJECTIVE: Low level light therapy has garnered significant interest within the past decade. The exact molecular mechanisms of how red and near infrared light result in physiologic modulation are not fully understood. Heme moieties and copper within cells are red and near infrared light photoreceptors that induce the mitochondrial respiratory chain component cytochrome C oxidase, resulting in a cascade linked to cytoprotection and cellular metabolism. The copper centers in cytochrome C oxidase have a broad absorption range that peaks around 830 nm. Several in vitro and in vivo animal and human models exist that have demonstrated the benefits of red light and near infrared light for various conditions. Clinical applications for low level light therapy are varied. One study in particular demonstrated improved durable functional outcomes status post-stroke in patients treated with near infrared low level light therapy compared to sham treatment [1]. Despite previous data suggesting the beneficial effect in treating multiple conditions, including stroke, with low level light therapy, limited data exists that measures transmission in a human model. STUDY DESIGN/MATERIALS AND METHODS: To investigate this idea, we measured the transmission of near infrared light energy, using red light for purposes of comparison, through intact cadaver soft tissue, skull bones, and brain using a commercially available LED device at 830 nm and 633 nm. RESULTS: Our results demonstrate that near infrared measurably penetrates soft tissue, bone and brain parenchyma in the formalin preserved cadaveric model, in comparison to negligible red light transmission in the same conditions. CONCLUSION: These findings indicate that near infrared light can penetrate formalin fixed soft tissue, bone and brain and implicate that benefits observed in clinical studies are potentially related to direct action of near infrared light on neural tissue.

Near-infrared light-triggered theranostics for tumor-specific enhanced multimodal imaging and photothermal therapy

Directory of Open Access Journals (Sweden)

Wu B

2017-06-01

Full Text Available Bo Wu,1,* Bing Wan,2,* Shu-Ting Lu,1 Kai Deng,3 Xiao-Qi Li,1 Bao-Lin Wu,1 Yu-Shuang Li,1 Ru-Fang Liao,1 Shi-Wen Huang,3 Hai-Bo Xu1,2 1Department of Radiology, Zhongnan Hospital of Wuhan University, 2Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, 3Department of Chemistry, Key Laboratory of Biomedical Polymers, Ministry of Education, Wuhan University, Wuhan, People’s Republic of China *These authors contributed equally to this work Abstract: The major challenge in current clinic contrast agents (CAs and chemotherapy is the poor tumor selectivity and response. Based on the self-quench property of IR820 at high concentrations, and different contrast effect ability of Gd-DOTA between inner and outer of liposome, we developed “bomb-like” light-triggered CAs (LTCAs for enhanced CT/MRI/FI multimodal imaging, which can improve the signal-to-noise ratio of tumor tissue specifically. IR820, Iohexol and Gd-chelates were firstly encapsulated into the thermal-sensitive nanocarrier with a high concentration. This will result in protection and fluorescence quenching. Then, the release of CAs was triggered by near-infrared (NIR light laser irradiation, which will lead to fluorescence and MRI activation and enable imaging of inflammation. In vitro and in vivo experiments demonstrated that LTCAs with 808 nm laser irradiation have shorter T1 relaxation time in MRI and stronger intensity in FI compared to those without irradiation. Additionally, due to the high photothermal conversion efficiency of IR820, the injection of LTCAs was demonstrated to completely inhibit C6 tumor growth in nude mice up to 17 days after NIR laser irradiation. The results indicate that the LTCAs can serve as a promising platform for NIR-activated multimodal imaging and photothermal therapy. Keywords: light triggered, near-infrared light, tumor-specific, multimodal imaging, photothermal therapy, contrast agents

Trans-cranial infrared laser stimulation induces hemodynamic and metabolic response measured by broadband near infrared spectroscopy in vivo on human forehead (Conference Presentation)

Science.gov (United States)

Wang, Xinlong; Nalawade, Sahil Sunil; Reddy, Divya Dhandapani; Tian, Fenghua; Gonzalez-Lima, F.; Liu, Hanli

2017-02-01

Transcranial infrared laser stimulation (TILS) uses infrared light (lasers or LEDs) for nondestructive and non-thermal photobiomodulation on the human brain. Although TILS has shown its beneficial effects to a variety of neurological and psychological conditions, its physiological mechanism remains unknown. Cytochrome-c-oxidase (CCO), the last enzyme in the electron transportation chain, is proposed to be the primary photoacceptor of this infrared laser. In this study, we wish to validate this proposed mechanism. We applied 8 minutes in vivo TILS on the right forehead of 11 human participants with a 1064-nm laser. Broad-band near infrared spectroscopy (bb-NIRS) from 740-900nm was also employed near the TILS site to monitor hemodynamic and metabolic responses during the stimulation and 5-minute recovery period. For rigorous comparison, we also performed similar 8-min bb-NIR measurements under placebo conditions. A multi-linear regression analysis based on the modified Beer-Lambert law was performed to estimate concentration changes of oxy-hemoglobin (Δ[HbO]), deoxy-hemoglobin (Δ[Hb]), and cytochrome-c-oxidase (Δ[CCO]). We found that TILS induced significant increases of [CCO], [HbO] and a decrease of [Hb] with dose-dependent manner as compared with placebo treatments. Furthermore, strong linear relationships or interplays between [CCO] versus [HbO] and [CCO] versus [Hb] induced by TILS were observed in vivo for the first time. These relationships have clearly revealed close coupling/relationship between the hemodynamic oxygen supply and blood volume versus up-regulation of CCO induced by photobiomodulation. Our results demonstrate the tremendous potential of bb-NIRS as a non-invasive in vivo means to study photobiomodulation mechanisms and perform treatment evaluations of TILS.

Infrared laser damage thresholds in corneal tissue phantoms using femtosecond laser pulses

Science.gov (United States)

Boretsky, Adam R.; Clary, Joseph E.; Noojin, Gary D.; Rockwell, Benjamin A.

2018-02-01

Ultrafast lasers have become a fixture in many biomedical, industrial, telecommunications, and defense applications in recent years. These sources are capable of generating extremely high peak power that can cause laser-induced tissue breakdown through the formation of a plasma upon exposure. Despite the increasing prevalence of such lasers, current safety standards (ANSI Z136.1-2014) do not include maximum permissible exposure (MPE) values for the cornea with pulse durations less than one nanosecond. This study was designed to measure damage thresholds in corneal tissue phantoms in the near-infrared and mid-infrared to identify the wavelength dependence of laser damage thresholds from 1200-2500 nm. A high-energy regenerative amplifier and optical parametric amplifier outputting 100 femtosecond pulses with pulse energies up to 2 mJ were used to perform exposures and determine damage thresholds in transparent collagen gel tissue phantoms. Three-dimensional imaging, primarily optical coherence tomography, was used to evaluate tissue phantoms following exposure to determine ablation characteristics at the surface and within the bulk material. The determination of laser damage thresholds in the near-IR and mid-IR for ultrafast lasers will help to guide safety standards and establish the appropriate MPE levels for exposure sensitive ocular tissue such as the cornea. These data will help promote the safe use of ultrafast lasers for a wide range of applications.

Gold nanocages covered by smart polymers for controlled release with near-infrared light.

Science.gov (United States)

Yavuz, Mustafa S; Cheng, Yiyun; Chen, Jingyi; Cobley, Claire M; Zhang, Qiang; Rycenga, Matthew; Xie, Jingwei; Kim, Chulhong; Song, Kwang H; Schwartz, Andrea G; Wang, Lihong V; Xia, Younan

2009-12-01

Photosensitive caged compounds have enhanced our ability to address the complexity of biological systems by generating effectors with remarkable spatial/temporal resolutions. The caging effect is typically removed by photolysis with ultraviolet light to liberate the bioactive species. Although this technique has been successfully applied to many biological problems, it suffers from a number of intrinsic drawbacks. For example, it requires dedicated efforts to design and synthesize a precursor compound for each effector. The ultraviolet light may cause damage to biological samples and is suitable only for in vitro studies because of its quick attenuation in tissue. Here we address these issues by developing a platform based on the photothermal effect of gold nanocages. Gold nanocages represent a class of nanostructures with hollow interiors and porous walls. They can have strong absorption (for the photothermal effect) in the near-infrared while maintaining a compact size. When the surface of a gold nanocage is covered with a smart polymer, the pre-loaded effector can be released in a controllable fashion using a near-infrared laser. This system works well with various effectors without involving sophisticated syntheses, and is well suited for in vivo studies owing to the high transparency of soft tissue in the near-infrared region.

Interplay between up-regulation of cytochrome-c-oxidase and hemoglobin oxygenation induced by near-infrared laser

Science.gov (United States)

Wang, Xinlong; Tian, Fenghua; Soni, Sagar S.; Gonzalez-Lima, F.; Liu, Hanli

2016-08-01

Photobiomodulation, also known as low-level laser/light therapy (LLLT), refers to the use of red-to-near-infrared light to stimulate cellular functions for physiological or clinical benefits. The mechanism of LLLT is assumed to rely on photon absorption by cytochrome c oxidase (CCO), the terminal enzyme in the mitochondrial respiratory chain that catalyzes the reduction of oxygen for energy metabolism. In this study, we used broadband near-infrared spectroscopy (NIRS) to measure the LLLT-induced changes in CCO and hemoglobin concentrations in human forearms in vivo. Eleven healthy participants were administered with 1064-nm laser and placebo treatments on their right forearms. The spectroscopic data were analyzed and fitted with wavelength-dependent, modified Beer-Lambert Law. We found that LLLT induced significant increases of CCO concentration (Δ[CCO]) and oxygenated hemoglobin concentration (Δ[HbO]) on the treated site as the laser energy dose accumulated over time. A strong linear interplay between Δ[CCO] and Δ[HbO] was observed for the first time during LLLT, indicating a hemodynamic response of oxygen supply and blood volume closely coupled to the up-regulation of CCO induced by photobiomodulation. These results demonstrate the tremendous potential of broadband NIRS as a non-invasive, in vivo means to study mechanisms of photobiomodulation and perform treatment evaluations of LLLT.

Mid-infrared quantum cascade laser spectroscopy probing of the ...

Indian Academy of Sciences (India)

Aparajeo Chattopadhyay

2018-05-07

May 7, 2018 ... cm3 molecule. −1 s. −1 ... Quantum cascade laser; time-resolved mid-infrared spectroscopy; transient absorption; peroxy radicals .... peak of the laser emission profile. .... cal with O2 is a termolecular reaction (Eq. 3) and the.

Laser capture microdissection: Arcturus(XT) infrared capture and UV cutting methods.

Science.gov (United States)

Gallagher, Rosa I; Blakely, Steven R; Liotta, Lance A; Espina, Virginia

2012-01-01

Laser capture microdissection (LCM) is a technique that allows the precise procurement of enriched cell populations from a heterogeneous tissue under direct microscopic visualization. LCM can be used to harvest the cells of interest directly or can be used to isolate specific cells by ablating the unwanted cells, resulting in histologically enriched cell populations. The fundamental components of laser microdissection technology are (a) visualization of the cells of interest via microscopy, (b) transfer of laser energy to a thermolabile polymer with either the formation of a polymer-cell composite (capture method) or transfer of laser energy via an ultraviolet laser to photovolatize a region of tissue (cutting method), and (c) removal of cells of interest from the heterogeneous tissue section. Laser energy supplied by LCM instruments can be infrared (810 nm) or ultraviolet (355 nm). Infrared lasers melt thermolabile polymers for cell capture, whereas ultraviolet lasers ablate cells for either removal of unwanted cells or excision of a defined area of cells. LCM technology is applicable to an array of applications including mass spectrometry, DNA genotyping and loss-of-heterozygosity analysis, RNA transcript profiling, cDNA library generation, proteomics discovery, and signal kinase pathway profiling. This chapter describes the unique features of the Arcturus(XT) laser capture microdissection instrument, which incorporates both infrared capture and ultraviolet cutting technology in one instrument, using a proteomic downstream assay as a model.

Infrared technique for decoding of invisible laser markings

Science.gov (United States)

Haferkamp, Heinz; Jaeschke, Peter; Stein, Johannes; Goede, Martin

2002-03-01

Counterfeiting and product piracy continues to be an important issue not only for the Western industry, but also for the society in general. Due to the drastic increase in product imitation and the request for plagiarism protection as well as for reducing thefts there is a high interest in new protection methods providing new security features. The method presented here consists of security markings which are included below paint layers. These markings are invisible for the human eye due to the non-transparency of the upper layers in the visible spectral range. However, the markings can be detected by an infrared technique taking advantage on the partial transparency of the upper paint layers in the IR-region. Metal sheets are marked using laser radiation. The beam of a Nd:YAG-laser provides a modification of the surface structure, resulting in dark markings due to the annealing effect. After coating of the laser-marked material, the markings are invisible for the bare eye. In order to read out the invisible information below the coating, an infrared reflection technique is used. The samples are illuminated with halogen lamps or infrared radiators. Many coating materials (i. e. paints) show a certain transparency in the mid-infrared region, especially between 3 - 5 micrometers . The reflected radiation is detected using an IR-camera with a sensitivity range from 3.4 - 5 micrometers . Due to the different reflection properties between the markings and their surrounding, the information can be detected.

Para-hydrogen raman laser and its application to laser induced chemistry

International Nuclear Information System (INIS)

Tashiro, Hideo

1988-01-01

The report outlines the mechanism of the para-hydrogen Raman laser as a infrared light source, and its application to laser induced chemistry. The Stoke's wave number after a Raman shift is equal to the difference between the wave number of the CO 2 laser used for excitation and the rotation Raman wave number of the hydrogen molecule. A Raman laser can serve as an infrared source. CO 2 laser oscillation beam in the range of 9∼11 micrometers is selected and the frequency of infrared beam is varied by changing the wave number of the CO 2 laser beam. A problem with the Raman laser is that the Raman scatterring gain is small due to a large wavelength. In developing equipment, a special mechanism is required to solve this problem. A Raman laser comprises a CO 2 laser for excitation and multi-pulse Raman cells. The combination of a TEA oscillator and amplifiers gives CO 2 pulses with a peak power of about several tens of MW. Many heavy metal compounds including fluorides, carbonyl compounds and other organic compounds, absorb light with wavelengths in the same range as those of the Raman laser. Such compounds can be dissociated directly by applying Raman laser beams. The laser will be helpful for separation of isotopes, etc. (Nogami, K.)

The origin of the infrared light of cataclysmic variable stars

International Nuclear Information System (INIS)

Berriman, G.; Szkody, P.; Capps, R.W.

1985-01-01

This paper presents a model-independent overview of the origin of the near infrared (1-2 μm) light of a sample of 28 cataclysmic binary stars, largely dwarf novae in quiescence. The infrared light comes from the red dwarf that supplies matter to the white dwarf companion and the accretion disc around the white dwarf. The complex nature of the disc prevents near-infrared photometry from being a good probe of the red dwarfs, even in those systems where they are seen in the visual. All that can be found reliably is an upper limit to the proportion light that the red dwarfs supply, and consequently lower limits to the distances to the systems. The infrared light of the discs comes from opaque material and from the optically thin gas that gives rise to the visual and UV emission lines. (author)

The design of infrared laser radar for vehicle initiative safety

Science.gov (United States)

Gong, Ping; Xu, Xi-ping; Li, Xiao-yu; Li, Tian-zhi; Liu, Yu-long; Wu, Jia-hui

2013-09-01

Laser radar for vehicle is mainly used in advanced vehicle on-board active safety systems, such as forward anti-collision systems, active collision warning systems and adaptive cruise control systems, etc. Laser radar for vehicle plays an important role in the improvement of vehicle active safety and the reduction of traffic accidents. The stability of vehicle active anti-collision system in dynamic environment is still one of the most difficult problems to break through nowadays. According to people's driving habit and the existed detecting technique of sensor, combining the infrared laser range and galvanometer scanning technique , design a 3-D infrared laser radar which can be used to assist navigation, obstacle avoidance and the vehicle's speed control for the vehicle initiative safety. The device is fixed to the head of vehicle. Then if an accident happened, the device could give an alarm to remind the driver timely to decelerate or brake down, by which way can people get the purpose of preventing the collision accidents effectively. To accomplish the design, first of all, select the core components. Then apply Zemax to design the transmitting and receiving optical system. Adopt 1550 nm infrared laser transmitter as emission unit in the device, a galvanometer scanning as laser scanning unit and an InGaAs-APD detector as laser echo signal receiving unit. Perform the construction of experimental system using FPGA and ARM as the core controller. The system designed in this paper can not only detect obstacle in front of the vehicle and make the control subsystem to execute command, but also transfer laser data to PC in real time. Lots of experiments using the infrared laser radar prototype are made, and main performance of it is under tested. The results of these experiments show that the imaging speed of the laser radar can reach up to 25 frames per second, the frame resolution of each image can reach 30×30 pixels, the horizontal angle resolution is about 6. 98

Separation of boron isotopes by infrared laser

International Nuclear Information System (INIS)

Suzuki, Kazuya

1995-01-01

Vibrationally excited chemical reaction of boron tribromide (BBr 3 ) with oxygen (O 2 ) is utilized to separate 10 B and 11 B. Infrared absorption of 10 BBr 3 is at 11.68μ and that of 11 BBr 3 is at 12.18μ. The wavelengths of ammonia laser made in the laboratory were mainly 11.71μ, 12.08μ and 12.26μ. Irradiation was done by focussing the laser with ZnSe lens on the sample gas (mixture of 1.5 torr of natural BBr 3 and 4.5 torr of O 2 ) in the reaction cell. Depletions of 10 BBr 3 and 11 BBr 3 due to chemical reaction of BBr 3 with O 2 was measured with infrared spectrometer. The maximum separation factor β( 10 B/ 11 B) obtained was about 4.5 (author)

Low-intensity red and infrared laser effects at high fluences on Escherichia coli cultures

Energy Technology Data Exchange (ETDEWEB)

Barboza, L.L.; Campos, V.M.A.; Magalhaes, L.A.G. [Instituto de Biologia Roberto Alcantara Gomes, Rio de Janeiro, RJ (Brazil). Departamento de Biofisica e Biometria; Paoli, F. [Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, MG (Brazil). Departamento de Morfologia; Fonseca, A.S., E-mail: adnfonseca@ig.com.br [Universidade Federal do Estado do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Departamento de Ciencias Fisiologicas

2015-10-15

Semiconductor laser devices are readily available and practical radiation sources providing wavelength tenability and high monochromaticity. Low-intensity red and near-infrared lasers are considered safe for use in clinical applications. However, adverse effects can occur via free radical generation, and the biological effects of these lasers from unusually high fluences or high doses have not yet been evaluated. Here, we evaluated the survival, filamentation induction and morphology of Escherichia coli cells deficient in repair of oxidative DNA lesions when exposed to low-intensity red and infrared lasers at unusually high fluences. Cultures of wild-type (AB1157), endonuclease III-deficient (JW1625-1), and endonuclease IV-deficient (JW2146-1) E. coli, in exponential and stationary growth phases, were exposed to red and infrared lasers (0, 250, 500, and 1000 J/cm{sup 2}) to evaluate their survival rates, filamentation phenotype induction and cell morphologies. The results showed that low-intensity red and infrared lasers at high fluences are lethal, induce a filamentation phenotype, and alter the morphology of the E. coli cells. Low-intensity red and infrared lasers have potential to induce adverse effects on cells, whether used at unusually high fluences, or at high doses. Hence, there is a need to reinforce the importance of accurate dosimetry in therapeutic protocols. (author)

Infrared presensitization photography at deuterium fluoride laser wavelengths

International Nuclear Information System (INIS)

Geary, J.M.; Ross, K.; Suter, K.

1989-01-01

Near-field irradiance distributions of a deuterium flouride laser system are obtained using infrared presensitization photography. This represents the shortest wavelength region to employ this technique thus far

Optics, light and lasers

CERN Document Server

Meschede, Dieter

2008-01-01

Starting from the concepts of classical optics, Optics, Light and Lasers introduces in detail the phenomena of linear and nonlinear light matter interaction, the properties of modern laser sources, and the concepts of quantum optics. Several examples taken from the scope of modern research are provided to emphasize the relevance of optics in current developments within science and technology. The text has been written for newcomers to the topic and benefits from the author's ability to explain difficult sequences and effects in a straightforward and easily comprehensible way. To this second, c

Transcranial infrared laser stimulation improves rule-based, but not information-integration, category learning in humans.

Science.gov (United States)

Blanco, Nathaniel J; Saucedo, Celeste L; Gonzalez-Lima, F

2017-03-01

This is the first randomized, controlled study comparing the cognitive effects of transcranial laser stimulation on category learning tasks. Transcranial infrared laser stimulation is a new non-invasive form of brain stimulation that shows promise for wide-ranging experimental and neuropsychological applications. It involves using infrared laser to enhance cerebral oxygenation and energy metabolism through upregulation of the respiratory enzyme cytochrome oxidase, the primary infrared photon acceptor in cells. Previous research found that transcranial infrared laser stimulation aimed at the prefrontal cortex can improve sustained attention, short-term memory, and executive function. In this study, we directly investigated the influence of transcranial infrared laser stimulation on two neurobiologically dissociable systems of category learning: a prefrontal cortex mediated reflective system that learns categories using explicit rules, and a striatally mediated reflexive learning system that forms gradual stimulus-response associations. Participants (n=118) received either active infrared laser to the lateral prefrontal cortex or sham (placebo) stimulation, and then learned one of two category structures-a rule-based structure optimally learned by the reflective system, or an information-integration structure optimally learned by the reflexive system. We found that prefrontal rule-based learning was substantially improved following transcranial infrared laser stimulation as compared to placebo (treatment X block interaction: F(1, 298)=5.117, p=0.024), while information-integration learning did not show significant group differences (treatment X block interaction: F(1, 288)=1.633, p=0.202). These results highlight the exciting potential of transcranial infrared laser stimulation for cognitive enhancement and provide insight into the neurobiological underpinnings of category learning. Copyright © 2017 Elsevier Inc. All rights reserved.

Silicon isotope separation utilizing infrared multiphoton dissociation of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser light

Energy Technology Data Exchange (ETDEWEB)

Yokoyama, Atsushi; Ohba, Hironori; Hashimoto, Masashi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishii, Takeshi; Ohya, Akio [Nuclear Development Corp., Tokai, Ibaraki (Japan); Arai, Shigeyoshi [Hill Research Co. Ltd., Tokyo (Japan)

2002-08-01

Silicon isotope separation has been done by utilizing the Infrared Multiphoton Dissociation (IRMPD) of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser lights. The two-color excitation method improved the separation efficiency keeping the high enrichment factors. For example, 99.74% of {sup 28}Si was obtained at 49.63% dissociation of Si{sub 2}F{sub 6} after the simultaneous irradiation of 200 pulses with 966.23 cm{sup -1} photons (0.084 J/cm{sup 2}) and 954.55 cm{sup -1} photons (0.658 J/cm{sup 2}), while 2000 pulses were needed to obtain 99.35% of {sup 28}Si at 35.6% dissociation in the case of only one-color irradiation at 954.55 cm{sup -1} (0.97 J/cm{sup 2}). (author)

Effects of near infrared laser radiation associated with photoabsorbing cream in preventing white spot lesions around orthodontic brackets: an in vitro study.

Science.gov (United States)

Lacerda, Ângela Sueli Soares Braga; Hanashiro, Fernando Seishim; de Sant'Anna, Giselle Rodrigues; Steagall Júnior, Washington; Barbosa, Patrícia Silva; de Souza-Zaroni, Wanessa Christine

2014-12-01

The present study aims to investigate the effect of a low-power infrared laser on the inhibition of bovine enamel demineralization around orthodontic brackets. Near infrared lasers have been suggested as alternative approaches because they may produce an increase in resistance to dental caries. Forty-eight blocks of enamel obtained from bovine incisor teeth were divided into six groups: Group 1 (control), without treatment; Group 2 (C), photoabsorbing cream; Group 3 (CF), photoabsorbing cream with fluoride; Group 4 (L), irradiation with low-level infrared laser (λ=830 nm) at an energy density of 4.47 J/cm2; Group 5 (L+C), photoabsorbing cream followed by low-level infrared laser irradiation; and Group 6 (L+CF), photoabsorbing cream with fluoride followed by low-level infrared laser irradiation. After these procedures, the enamel blocks received an assortment of orthodontic brackets and were then submitted to pH cycling to simulate a highly cariogenic challenge. The enamel surface demineralization around the orthodontic brackets, according to the different treatments, was quantified by fluorescence loss analysis by quantitative light-induced fluorescence (QLF). The fluorescence loss, expressed as ΔF (percentage of loss fluorescence), was statistically examined by analysis of variance and the Tukey test. The control group (-10.48±2.85) was statistically similar to Group C (-14.52±7.80), which presented the lowest values of ΔF when compared with Groups FC (-3.67±3.21), L (-2.79±1.68), CL (-1.05±0:50), and CFL (-0.60±0:43). However, Groups FC, L, CL, and CFL showed no statistically significant differences among them. It can be concluded that both the low-level infrared laser and photoabsorbing cream with fluoride were effective in inhibiting the development of caries in enamel around orthodontic brackets, even in situations of high cariogenic challenge.

Low-intensity infrared lasers alter actin gene expression in skin and muscle tissue

International Nuclear Information System (INIS)

Fonseca, A S; Mencalha, A L; Campos, V M A; Ferreira-Machado, S C; Peregrino, A A F; Magalhães, L A G; Geller, M; Paoli, F

2013-01-01

The biostimulative effect of low-intensity lasers is the basis for treatment of diseases in soft tissues. However, data about the influence of biostimulative lasers on gene expression are still scarce. The aim of this work was to evaluate the effects of low-intensity infrared lasers on the expression of actin mRNA in skin and muscle tissue. Skin and muscle tissue of Wistar rats was exposed to low-intensity infrared laser radiation at different fluences and frequencies. One and 24 hours after laser exposure, tissue samples were withdrawn for total RNA extraction, cDNA synthesis and evaluation of actin gene expression by quantitative polymerase chain reaction. The data obtained show that laser radiation alters the expression of actin mRNA differently in skin and muscle tissue of Wistar rats depending of the fluence, frequency and time after exposure. The results could be useful for laser dosimetry, as well as to justify the therapeutic protocols for treatment of diseases of skin and muscle tissues based on low-intensity infrared laser radiation. (paper)

Enhanced optical confinement of dye-doped dielectric nanoparticles using a picosecond-pulsed near-infrared laser

International Nuclear Information System (INIS)

Kittiravechote, A; Chiang, W-Y; Usman, A; Liau, I; Masuhara, H

2014-01-01

We demonstrate a novel strategy to increase the capability of confining numerous dye-doped polymeric nanobeads (diameter 100 nm) with laser trapping. Unlike most classical works of optical trapping that address mainly the stiffness of the optical trap, our work concerns an increase in the number of particles confined near the laser focus. We developed an imaging system of light scattering in which a condenser lamp was employed to illuminate the focal plane of the objective lens, and the scattering of the incoherent light was specifically measured to determine the number of confined nanobeads. In contrast to preceding work that used mainly continuous-wave or femtosecond-pulsed lasers, we employed a picosecond-pulsed laser with the half-wavelength of the laser particularly falling within the absorption band of the dopant. Our results show that the number of doped nanobeads held by the laser is significantly greater than that of the bare nanobeads of the same dimension. In striking contrast, the confinement of the nanobeads of the two types was comparable when a continuous-wave laser of the same wavelength and power was employed. The number of confined dye-doped nanobeads increased nonlinearly with the power of the pulsed laser; this dependence was fitted satisfactorily with a second-order polynomial. Supported by theoretical analysis, we attribute the enhanced confinement of doped nanobeads in part to an increased effective refractive index resulting from two-photon resonance between the optical field of the laser and the dopant of the nanobead. We envisage that our findings would evoke applications that benefit from controlled confinement or aggregation of nanomaterials with the employment of near-infrared pulsed lasers. (letter)

Threshold Characteristics of Slow-Light Photonic Crystal Lasers

DEFF Research Database (Denmark)

Xue, Weiqi; Yu, Yi; Ottaviano, Luisa

2016-01-01

The threshold properties of photonic crystal quantum dot lasers operating in the slow-light regime are investigated experimentally and theoretically. Measurements show that, in contrast to conventional lasers, the threshold gain attains a minimum value for a specific cavity length. The experimental...... results are explained by an analytical theory for the laser threshold that takes into account the effects of slow light and random disorder due to unavoidable fabrication imperfections. Longer lasers are found to operate deeper into the slow-light region, leading to a trade-off between slow-light induced...

Rugged and compact mid-infrared solid-state laser for avionics applications

CSIR Research Space (South Africa)

Esser, MJD

2009-11-01

Full Text Available In order to demonstrate the feasibility of a helicopter-based application using advanced laser technology, the authors have developed a rugged and compact mid-infrared solid-state laser. The requirement for the laser was to simultaneously emit at 2...

High-speed high-sensitivity infrared spectroscopy using mid-infrared swept lasers (Conference Presentation)

Science.gov (United States)

Childs, David T. D.; Groom, Kristian M.; Hogg, Richard A.; Revin, Dmitry G.; Cockburn, John W.; Rehman, Ihtesham U.; Matcher, Stephen J.

2016-03-01

Infrared spectroscopy is a highly attractive read-out technology for compositional analysis of biomedical specimens because of its unique combination of high molecular sensitivity without the need for exogenous labels. Traditional techniques such as FTIR and Raman have suffered from comparatively low speed and sensitivity however recent innovations are challenging this situation. Direct mid-IR spectroscopy is being speeded up by innovations such as MEMS-based FTIR instruments with very high mirror speeds and supercontinuum sources producing very high sample irradiation levels. Here we explore another possible method - external cavity quantum cascade lasers (EC-QCL's) with high cavity tuning speeds (mid-IR swept lasers). Swept lasers have been heavily developed in the near-infrared where they are used for non-destructive low-coherence imaging (OCT). We adapt these concepts in two ways. Firstly by combining mid-IR quantum cascade gain chips with external cavity designs adapted from OCT we achieve spectral acquisition rates approaching 1 kHz and demonstrate potential to reach 100 kHz. Secondly we show that mid-IR swept lasers share a fundamental sensitivity advantage with near-IR OCT swept lasers. This makes them potentially able to achieve the same spectral SNR as an FTIR instrument in a time x N shorter (N being the number of spectral points) under otherwise matched conditions. This effect is demonstrated using measurements of a PDMS sample. The combination of potentially very high spectral acquisition rates, fundamental SNR advantage and the use of low-cost detector systems could make mid-IR swept lasers a powerful technology for high-throughput biomedical spectroscopy.

Near-Infrared-Light-Responsive Magnetic DNA Microgels for Photon- and Magneto-Manipulated Cancer Therapy.

Science.gov (United States)

Wang, Yitong; Wang, Ling; Yan, Miaomiao; Dong, Shuli; Hao, Jingcheng

2017-08-30

Functional DNA molecules have been introduced into polymer-based nanocarrier systems to incorporate chemotherapy drugs for cancer therapy. Here is the first report of dual-responsive microgels composed of a core of Au nanorods and a shell of magnetic ionic liquid and DNA moieties in the cross-linking network simultaneously, as effective drug delivery vectors. TEM images indicated a magnetic polymer shell has an analogous "doughnut" shape which loosely surround the AuNRs core. When irradiated with a near-infrared-light (near-IR) laser, Au nanorods are the motors which convert the light to heat, leading to the release of the encapsulated payloads with high controllability. DNA acts not only as a cross-linker agent, but also as a gatekeeper to regulate the release of drugs. The internalization study and MTT assay confirm that these core-shell DNA microgels are excellent candidates which can enhance the cytotoxicity of cancer cells controlled by near-IR laser and shield the high toxicity of chemotherapeutic agents to improve the killing efficacy of chemotherapeutic agents efficiently in due course.

Efficient and stable laser-driven white lighting

Directory of Open Access Journals (Sweden)

Kristin A. Denault

2013-07-01

Full Text Available Laser-based white lighting offers a viable option as an efficient and color-stable high-power solid-state white light source. We show that white light generation is possible using blue or near-UV laser diodes in combination with yellow-emitting cerium-substituted yttrium aluminum garnet (YAG:Ce or a mixture of red-, green-, and blue-emitting phosphors. A variety of correlated color temperatures (CCT are achieved, ranging from cool white light with a CCT of 4400 K using a blue laser diode to a warm white light with a CCT of 2700 K using a near-UV laser diode, with respective color rendering indices of 57 and 95. The luminous flux of these devices are measured to be 252 lm and 53 lm with luminous efficacies of 76 lm/W and 19 lm/W, respectively. An estimation of the maximum efficacy of a device comprising a blue laser diode in combination with YAG:Ce is calculated and the results are used to optimize the device.

Infrared synchrotron radiation from electron storage rings

International Nuclear Information System (INIS)

Duncan, W.D.; Williams, G.P.

1983-01-01

Simple and useful approximations, valid at infrared wavelengths, to the equations for synchrotron radiation are presented and used to quantify the brightness and power advantage of current synchrotron radiation light sources over conventional infrared broadband laboratory sources. The Daresbury Synchrotron Radiation Source (SRS) and the Brookhaven National Synchrotron Light Source (vacuum ultraviolet) [NSLS(VUV)] storage rings are used as examples in the calculation of the properties of infrared synchrotron radiation. The pulsed nature of the emission is also discussed, and potential areas of application for the brightness, power, and time structure advantages are presented. The use of infrared free electron lasers and undulators on the next generation of storage ring light sources is briefly considered

Laser and intense pulsed light hair removal technologies

DEFF Research Database (Denmark)

Haedersdal, M; Beerwerth, F; Nash, J F

2011-01-01

Light-based hair removal (LHR) is one of the fastest growing, nonsurgical aesthetic cosmetic procedures in the United States and Europe. A variety of light sources including lasers, e.g. alexandrite laser (755 nm), pulsed diode lasers (800, 810 nm), Nd:YAG laser (1064 nm) and broad-spectrum intense...

Non-collinear upconversion of infrared light

DEFF Research Database (Denmark)

Pedersen, Christian; Hu, Qi; Høgstedt, Lasse

2014-01-01

Two dimensional mid-infrared upconversion imaging provides unique spectral and spatial information showing good potential for mid- infrared spectroscopy and hyperspectral imaging. However, to extract spectral or spatial information from the upconverted images an elaborate model is needed, which...... includes non-collinear interaction. We derive here a general theory providing the far field of the upconverted light when two arbitrary fields interact inside a non linear crystal. Theoretical predictions are experimentally verified for incoherent radiation and subsequently applied to previously published...

Transdermal gelation of methacrylated macromers with near-infrared light and gold nanorods

International Nuclear Information System (INIS)

Gramlich, William M; Holloway, Julianne L; Rai, Reena; Burdick, Jason A

2014-01-01

Injectable hydrogels provide locally controlled tissue bulking and a means to deliver drugs and cells to the body. The formation of hydrogels in vivo may involve the delivery of two solutions that spontaneously crosslink when mixed, with pH or temperature changes, or with light (e.g., visible or ultraviolet). With these approaches, control over the kinetics of gelation, introduction of the initiation trigger (e.g., limited penetration of ultraviolet light through tissues), or alteration of the material physical properties (e.g., mechanics) may be difficult to achieve. To overcome these limitations, we used the interaction of near-infrared (NIR) light with gold nanorods (AuNRs) to generate heat through the photothermal effect. NIR light penetrates tissues to a greater extent than other wavelengths and provides a means to indirectly initiate radical polymerization. Specifically, this heating coupled with a thermal initiator (VA-044) produced radicals that polymerized methacrylated hyaluronic acid (MeHA) and generated hydrogels. A range of VA-044 concentrations changed the gelation time, yielding a system stable at 37 ° C for 22 min that gels quickly (∼3 min) when heated to 55 ° C. With a constant irradiation time (10 min) and laser power (0.3 W), different VA-044 and AuNR concentrations tuned the compressive modulus of the hydrogel. By changing the NIR irradiation time we attained a wide range of moduli at a set solution composition. In vivo mouse studies confirmed that NIR laser irradiation through tissue could gel an injected precursor solution transdermally. (paper)

Transdermal gelation of methacrylated macromers with near-infrared light and gold nanorods

Science.gov (United States)

Gramlich, William M.; Holloway, Julianne L.; Rai, Reena; Burdick, Jason A.

2014-01-01

Injectable hydrogels provide locally controlled tissue bulking and a means to deliver drugs and cells to the body. The formation of hydrogels in vivo may involve the delivery of two solutions that spontaneously crosslink when mixed, with pH or temperature changes, or with light (e.g., visible or ultraviolet). With these approaches, control over the kinetics of gelation, introduction of the initiation trigger (e.g., limited penetration of ultraviolet light through tissues), or alteration of the material physical properties (e.g., mechanics) may be difficult to achieve. To overcome these limitations, we used the interaction of near-infrared (NIR) light with gold nanorods (AuNRs) to generate heat through the photothermal effect. NIR light penetrates tissues to a greater extent than other wavelengths and provides a means to indirectly initiate radical polymerization. Specifically, this heating coupled with a thermal initiator (VA-044) produced radicals that polymerized methacrylated hyaluronic acid (MeHA) and generated hydrogels. A range of VA-044 concentrations changed the gelation time, yielding a system stable at 37 ° C for 22 min that gels quickly (˜3 min) when heated to 55 ° C. With a constant irradiation time (10 min) and laser power (0.3 W), different VA-044 and AuNR concentrations tuned the compressive modulus of the hydrogel. By changing the NIR irradiation time we attained a wide range of moduli at a set solution composition. In vivo mouse studies confirmed that NIR laser irradiation through tissue could gel an injected precursor solution transdermally.

New Opportunities in Mid-Infrared Emission Control

Directory of Open Access Journals (Sweden)

Peter Geiser

2015-09-01

Full Text Available Tunable laser absorption spectroscopy (TLAS has been well accepted as a preferred measurement technique for many industrial applications in recent years, especially for in situ applications. Previously, mainly near-infrared lasers have been used in TLAS sensors. The advent of compact mid-infrared light sources, like quantum cascade lasers and interband cascade lasers, has made it possible to detect gases with better sensitivity by utilizing fundamental absorption bands and to measure species that do not have any absorption lines in the near-infrared spectral region. This technological advancement has allowed developing new sensors for gases, such as nitric oxide and sulfur dioxide, for industrial applications. Detection limits of better than 1 ppm·m for nitric oxide and better than 10 ppm·m for sulfur dioxide are demonstrated in field experiments.

Comparison of human skin opto-thermal response to near-infrared and visible laser irradiations: a theoretical investigation

Energy Technology Data Exchange (ETDEWEB)

Dai Tianhong [Department of Bioengineering, Rice University, Houston, TX 77251 (United States); Pikkula, Brian M [Department of Bioengineering, Rice University, Houston, TX 77251 (United States); Wang, Lihong V [Department of Biomedical Engineering, Texas A and M University, College Station, TX 77843 (United States); Anvari, Bahman [Department of Bioengineering, Rice University, Houston, TX 77251 (United States)

2004-11-07

Near-infrared wavelengths are absorbed less by epidermal melanin, and penetrate deeper into human skin dermis and blood than visible wavelengths. Therefore, laser irradiation using near-infrared wavelengths may improve the therapeutic outcome of cutaneous hyper-vascular malformations in moderately to heavily pigmented skin patients and those with large-sized blood vessels or blood vessels extending deeply into the skin. A mathematical model composed of a Monte Carlo algorithm to estimate the distribution of absorbed light, numerical solution of a bio-heat diffusion equation to calculate the transient temperature distribution, and a damage integral based on an empirical Arrhenius relationship to quantify the tissue damage was utilized to investigate the opto-thermal response of human skin to near-infrared and visible laser irradiations in conjunction with cryogen spray cooling. In addition, the thermal effects of a single continuous laser pulse and micropulse-composed laser pulse profiles were compared. Simulation results indicated that a 940 nm wavelength induces improved therapeutic outcome compared with a 585 and 595 nm wavelengths for the treatment of patients with large-sized blood vessels and moderately to heavily pigmented skin. On the other hand, a 585 nm wavelength shows the best efficacy in treating small-sized blood vessels, as characterized by the largest laser-induced blood vessel damage depth compared with 595 and 940 nm wavelengths. Dermal blood content has a considerable effect on the threshold incident dosage for epidermal damage, while the effect of blood vessel size is minimal. For the same macropulse duration and incident dosage, a micropulse-composed pulse profile results in higher peak temperature at the basal layer of skin epidermis than an ideal single continuous pulse profile.

Fractionated bipolar radiofrequency and bipolar radiofrequency potentiated by infrared light for treating striae: A prospective randomized, comparative trial with objective evaluation.

Science.gov (United States)

Harmelin, Yona; Boineau, Dominique; Cardot-Leccia, Nathalie; Fontas, Eric; Bahadoran, Philippe; Becker, Anne-Lise; Montaudié, Henri; Castela, Emeline; Perrin, Christophe; Lacour, Jean-Philippe; Passeron, Thierry

2016-03-01

Very few treatments for striae are based on prospective randomized trials. The objective of this study was to assess the efficacy of bipolar fractional radiofrequency and bipolar radiofrequency potentiated with infrared light, alone or combined, for treating abdominal stretch marks. Bicentric prospective interventional randomized controlled trial in the department of Dermatology of University Hospital of Nice and Aesthetics Laser Center of Bordeaux, France. Men and women of age 18 years or above, who presented for the treatment of mature or immature abdominal striae were included. The patients' abdomens were divided into four equal quadrants. Bipolar radiofrequency potentiated with infrared light and fractional bipolar radiofrequency were applied, alone or combined, and compared to the remaining untreated quadrant. The main criterion of evaluation was the measurement of depth of striae, using 3D photography at 6 months follow-up. A global assessment was also rated by the physician performing the treatment and by the patients. Histological analysis and confocal laser microscopy were additionally performed. A total of 22 patients were enrolled, and 384 striae were measured. In per protocol analysis mean striae depth was decreased by 21.64%, observed at 6 months follow-up with the combined approach, compared to an increase of 1.73% in the control group (P radiofrequency, combined with bipolar radiofrequency potentiated by infrared light, is an effective treatment of both immature and mature striae of the abdomen. © 2016 Wiley Periodicals, Inc.

Single bead near-infrared random laser based on silica-gel infiltrated with Rhodamine 640

Science.gov (United States)

Moura, André L.; Barbosa-Silva, Renato; Dominguez, Christian T.; Pecoraro, Édison; Gomes, Anderson S. L.; de Araújo, Cid B.

2018-04-01

Photoluminescence properties of single bead silica-gel (SG) embedded with a laser-dye were studied aiming at the operation of near-infrared (NIR) Random Lasers (RLs). The operation of RLs in the NIR spectral region is especially important for biological applications since the optical radiation has deep tissue penetration with negligible damage. Since laser-dyes operating in the NIR have poor stability and are poor emitters, ethanol solutions of Rhodamine 640 (Rh640) infiltrated in SG beads were used. The Rh640 concentrations in ethanol varied from 10-5 to 10-2 M and the excitation at 532 nm was made by using a 7 ns pulsed laser. The proof-of-principle RL scheme herein presented was adopted in order to protect the dye-molecules from the environment and to favor formation of aggregates. The RL emission from ≈650 nm to 720 nm, beyond the typical Rh640 monomer and dimer wavelengths emissions range, was attributed to the trade-off between reabsorption and reemission processes along the light pathways inside the SG bead and the contribution of Rh640 aggregates.

Laser discrimination by stimulated emission of a phosphor

Science.gov (United States)

Mathur, V. K.; Chakrabarti, K.

1991-01-01

A method for discriminating sources of UV, near infrared, and far infrared laser radiation was discovered. This technology is based on the use of a single magnesium sulfide phosphor doubly doped with rare earth ions, which is thermally/optically stimulated to generate colors correlatable to the incident laser radiation. The phosphor, after initial charging by visible light, exhibits green stimulated luminescence when exposed to a near infrared source (Nd: YAG laser). On exposure to far infrared sources (CO2 laser) the phosphor emission changes to orange color. A UV laser produces both an orange red as well as green color. A device using this phosphor is useful for detecting the laser and for discriminating between the near infrared, far infrared, and UV lasers. The technology is also capable of infrared laser diode beam profiling since the radiation source leaves an imprint on the phosphor that can be photographed. Continued development of the technology offers potential for discrimination between even smaller bandwidths within the infrared spectrum, a possible aid to communication or wavemixing devices that need to rapidly identify and process optical signals.

A near infrared laser frequency comb for high precision Doppler planet surveys

Directory of Open Access Journals (Sweden)

Bally J.

2011-07-01

Full Text Available Perhaps the most exciting area of astronomical research today is the study of exoplanets and exoplanetary systems, engaging the imagination not just of the astronomical community, but of the general population. Astronomical instrumentation has matured to the level where it is possible to detect terrestrial planets orbiting distant stars via radial velocity (RV measurements, with the most stable visible light spectrographs reporting RV results the order of 1 m/s. This, however, is an order of magnitude away from the precision needed to detect an Earth analog orbiting a star such as our sun, the Holy Grail of these efforts. By performing these observations in near infrared (NIR there is the potential to simplify the search for distant terrestrial planets by studying cooler, less massive, much more numerous class M stars, with a tighter habitable zone and correspondingly larger RV signal. This NIR advantage is undone by the lack of a suitable high precision, high stability wavelength standard, limiting NIR RV measurements to tens or hundreds of m/s [1, 2]. With the improved spectroscopic precision provided by a laser frequency comb based wavelength reference producing a set of bright, densely and uniformly spaced lines, it will be possible to achieve up to two orders of magnitude improvement in RV precision, limited only by the precision and sensitivity of existing spectrographs, enabling the observation of Earth analogs through RV measurements. We discuss the laser frequency comb as an astronomical wavelength reference, and describe progress towards a near infrared laser frequency comb at the National Institute of Standards and Technology and at the University of Colorado where we are operating a laser frequency comb suitable for use with a high resolution H band astronomical spectrograph.

A dual far-infrared laser diagnostic of magnetized plasmas

International Nuclear Information System (INIS)

Darrow, D.S.; Park, H.K.

1988-02-01

A dual far-infrared laser has been constructed and its properties have been exploited to probe tokamak-like discharges in the CDX toroidal device. Thermal variation of the difference frequency between the two far-infrared cavities is slow, though the cavities lack thermal stabilization, simply because their assembly on the same chassis exposes them to virtually identical temperature changes. The optical arrangement beyond the laser permits conversion within minutes between interferometry and density fluctuation observation, and within an hour between different operating wavelengths. Line-average densities of 2 /times/ 10 13 cm -3 and coherent fluctuations in the neighborhood of 20 kHz have been measured with this diagnostic. 15 refs., 5 figs., 2 tabs

Comparison of tissue damage caused by various laser systems with tissue tolerable plasma by light and laser scan microscopy

International Nuclear Information System (INIS)

Vandersee, Staffan; Lademann, Jürgen; Richter, Heike; Patzelt, Alexa; Lange-Asschenfeldt, Bernhard

2013-01-01

Tissue tolerable plasma (TTP) represents a novel therapeutic method with promising capabilities in the field of dermatological interventions, in particular disinfection but also wound antisepsis and regeneration. The energy transfer by plasma into living tissue is not easily educible, as a variety of features such as the medium’s actual molecule-stream, the ions, electrons and free radicals involved, as well as the emission of ultraviolet, visible and infrared light contribute to its increasingly well characterized effects. Thus, relating possible adversary effects, especially of prolonged exposure to a single component of the plasma’s mode of action, is difficult. Until now, severe adverse events connected to plasma exposure have not been reported when conducted according to existing therapeutic protocols. In this study, we have compared the tissue damage-potential of CO 2 and dye lasers with TTP in a porcine model. After exposure of pig ear skin to the three treatment modalities, all specimens were examined histologically and by means of laser scan microscopy (LSM). Light microscopical tissue damage could only be shown in the case of the CO 2 laser, whereas dye laser and plasma treatment resulted in no detectable impairment of the specimens. In the case of TTP, LSM examination revealed only an impairment of the uppermost corneal layers of the skin, thus stressing its safety when used in vivo. (letter)

Band Gap Distortion in Semiconductors Strongly Driven by Intense Mid-Infrared Laser Fields

Science.gov (United States)

Kono, J.; Chin, A. H.

2000-03-01

Crystalline solids non-resonantly driven by intense time-periodic electric fields are predicted to exhibit unusual band-gap distortion.(e.g., Y. Yacoby, Phys. Rev. 169, 610 (1968); L.C.M. Miranda, Solid State Commun. 45, 783 (1983); J.Z. Kaminski, Acta Physica Polonica A 83, 495(1993).) Such non-perturbative effects have not been observed to date because of the unavoidable sample damage due to the very high intensity required using conventional lasers ( 1 eV photon energy). Here, we report the first clear evidence of laser-induced bandgap shrinkage in semiconductors under intense mid-infrared (MIR) laser fields. The use of long-wavelength light reduces the required intensity and prohibits strong interband absorption, thereby avoiding the damage problem. The significant sub-bandgap absorption persists only during the existence of the MIR laser pulse, indicating the virtual nature of the effect. We show that this particular example of non-perturbative behavior, known as the dynamical Franz-Keldysh effect, occurs when the effective ponderomotive potential energy is comparable to the photon energy of the applied field. This work was supported by ONR, NSF, JST and NEDO.

DNA fragmentation and nuclear phenotype in tendons exposed to low-intensity infrared laser

Science.gov (United States)

de Paoli, Flavia; Ramos Cerqueira, Larissa; Martins Ramos, Mayara; Campos, Vera M.; Ferreira-Machado, Samara C.; Geller, Mauro; de Souza da Fonseca, Adenilson

2015-03-01

Clinical protocols are recommended in device guidelines outlined for treating many diseases on empirical basis. However, effects of low-intensity infrared lasers at fluences used in clinical protocols on DNA are controversial. Excitation of endogenous chromophores in tissues and free radicals generation could be described as a consequence of laser used. DNA lesions induced by free radicals cause changes in DNA structure, chromatin organization, ploidy degrees and cell death. In this work, we investigated whether low-intensity infrared laser therapy could alter the fibroblasts nuclei characteristics and induce DNA fragmentation. Tendons of Wistar rats were exposed to low-intensity infrared laser (830 nm), at different fluences (1, 5 and 10 J/cm2), in continuous wave (power output of 10mW, power density of 79.6 mW/cm2). Different frequencies were analyzed for the higher fluence (10 J/cm2), at pulsed emission mode (2.5, 250 and 2500 Hz), with the laser source at surface of skin. Geometric, densitometric and textural parameters obtained for Feulgen-stained nuclei by image analysis were used to define nuclear phenotypes. Significant differences were observed on the nuclear phenotype of tendons after exposure to laser, as well as, high cell death percentages was observed for all fluences and frequencies analyzed here, exception 1 J/cm2 fluence. Our results indicate that low-intensity infrared laser can alter geometric, densitometric and textural parameters in tendon fibroblasts nuclei. Laser can also induce DNA fragmentation, chromatin lost and consequently cell death, using fluences, frequencies and emission modes took out from clinical protocols.

Twin optically-pumped far-infrared CH3OH laser for plasma diagnostics

International Nuclear Information System (INIS)

Yamanaka, M.; Takeda, Y.; Tanigawa, S.; Nishizawa, A.

1980-01-01

A twin optically-pumped far-infrared CH 3 OH laser has been constructed for use in plasma diagnostics. The antisymmetric doublet due to the Raman-type resonant two-photon transition is reproducibly observed at 118.8 microns. With the 118.8-micron line, it is found that CH 3 OH absorption line center is 16 + or - 1 MHz higher than the pump 9.7-micron P(36) CO 2 laser line center. It is shown that the Raman-type resonant two-photon transition is useful in order to get several MHz phase modulation for the far-infrared laser interferometer. Some preliminary performances of this twin laser for the modulated interferometer are described

A review of laser and light therapy in melasma

Directory of Open Access Journals (Sweden)

M.K. Trivedi, BS, BA

2017-03-01

Full Text Available Melasma is a dysregulation of the homeostatic mechanisms that control skin pigmentation and excess pigment is produced. Traditional treatment approaches with topical medications and chemical peels are commonly used but due to the refractory and recurrent nature of melasma, patients often seek alternative treatment strategies such as laser and light therapy. Several types of laser and light therapy have been studied in the treatment of melasma. Intense pulsed light, low fluence Q-switched lasers, and non-ablative fractionated lasers are the most common lasers and light treatments that are currently performed. They all appear effective but there is a high level of recurrence with time and some techniques are associated with an increased risk for postinflammatory hyper- or hypopigmentation. The number and frequency of treatments varies by device type but overall, Q-switched lasers require the greatest number of treatment applications to see a benefit. Vascular-specific lasers do not appear to be effective for the treatment of melasma. Ablative fractionated lasers should be used with caution because they have a very high risk for postinflammatory hypo- and hyperpigmentation. The use of nonablative fractionated laser treatments compared with other laser and light options may result in slightly longer remission intervals. Picosecond lasers, fractional radiofrequency, and laser-assisted drug delivery are promising future approaches to treat melasma. The goal of this review is to summarize the efficacy and safety of the most commonly used laser and light therapies to treat melasma, briefly present future laser-based treatment options for patients with melasma, and provide recommendations for treatment on the basis of the reviewed information.

All-Quantum-Dot Infrared Light-Emitting Diodes

KAUST Repository

Yang, Zhenyu

2015-12-22

© 2015 American Chemical Society. Colloidal quantum dots (CQDs) are promising candidates for infrared electroluminescent devices. To date, CQD-based light-emitting diodes (LEDs) have employed a CQD emission layer sandwiched between carrier transport layers built using organic materials and inorganic oxides. Herein, we report the infrared LEDs that use quantum-tuned materials for each of the hole-transporting, the electron-transporting, and the light-emitting layers. We successfully tailor the bandgap and band position of each CQD-based component to produce electroluminescent devices that exhibit emission that we tune from 1220 to 1622 nm. Devices emitting at 1350 nm achieve peak external quantum efficiency up to 1.6% with a low turn-on voltage of 1.2 V, surpassing previously reported all-inorganic CQD LEDs.

Metallic nano-cavity lasers at near infrared wavelengths

NARCIS (Netherlands)

Hill, M.T.; Stockman, M.I.

2009-01-01

There has been considerable interest in nano-cavity lasers, both from a scientific perspective for investigating fundamental properties of lasers and cavities, and also to produce smaller and better lasers for low-power applications. Light confinement on a wavelength scale has been reported in

Infrared and optical light curves of EX Hydrae and VW Hydri

International Nuclear Information System (INIS)

Sherrington, M.R.; Lawson, P.A.; King, A.R.; Jameson, R.F.

1980-01-01

Optical and infrared light curves of EX Hya (V and K) and VW Hyi (J and K) are presented. The infrared colours imply very large discs for these systems. It is also found for EX Hya that the structure of the light curves is non-repeatable. (author)

Development of cryo-cell for infrared Raman laser

International Nuclear Information System (INIS)

Harada, Tetsuro; Ohmori, Takao; Saito, Hideaki

1984-01-01

Laser isotope separation (LIS) for uranium enrichment is remarkable for its higher efficiency and cost effectiveness over the gaseous diffusion process. A prototype Raman Laser apparatus for uranium enrichment was developed and manufactured by IHI for the Institute of Physical and Chemical Research. This apparatus is capable of emitting tunable infrared Laser beam of a wave length from 13 μm to 17 μm from its multiple pass resonator by injecting a highly coherent CO 2 Laser beam into the para-hydrogen gas vessel (kept at 100 K) to induce Raman scattering. This paper describes the Laser oscillation mechanism and the structure of the multiple pass cell; it also discusses the technical aspects that are essential for a Raman Laser apparatus. Moreover, the cooling characteristics of the present apparatus are reported by analyzing the results of tests conducted in actual service thermal conditions. (author)

Optical system design with common aperture for mid-infrared and laser composite guidance

Science.gov (United States)

Zhang, Xuanzhi; Yang, Zijian; Sun, Ting; Yang, Huamei; Han, Kunye; Hu, Bo

2017-02-01

When the field of operation of precision strike missiles is more and more complicated, autonomous seekers will soon encounter serious difficulties, especially with regard to low signature targets and complex scenarios. So the dual-mode sensors combining an imaging sensor with a semi-active laser seeker are conceived to overcome these specific problems. Here the sensors composed a dual field of view mid-infrared thermal imaging camera and a laser range finder have the common optical aperture which produced the minization of seeker construction. The common aperture optical systems for mid-infrared and laser dual-mode guildance have been developed, which could meet the passive middle infrared high-resolution imaging and the active laser high-precision indication and ranging. The optical system had good image quality, and fulfilled the performance requirement of seeker system. The design and expected performance of such a dual-mode optical system will be discussed.

Up-regulation of cerebral cytochrome-c-oxidase and hemodynamics by transcranial infrared laser stimulation: A broadband near-infrared spectroscopy study.

Science.gov (United States)

Wang, Xinlong; Tian, Fenghua; Reddy, Divya D; Nalawade, Sahil S; Barrett, Douglas W; Gonzalez-Lima, Francisco; Liu, Hanli

2017-12-01

Transcranial infrared laser stimulation (TILS) is a noninvasive form of brain photobiomulation. Cytochrome-c-oxidase (CCO), the terminal enzyme in the mitochondrial electron transport chain, is hypothesized to be the primary intracellular photoacceptor. We hypothesized that TILS up-regulates cerebral CCO and causes hemodynamic changes. We delivered 1064-nm laser stimulation to the forehead of healthy participants ( n = 11), while broadband near-infrared spectroscopy was utilized to acquire light reflectance from the TILS-treated cortical region before, during, and after TILS. Placebo experiments were also performed for accurate comparison. Time course of spectroscopic readings were analyzed and fitted to the modified Beer-Lambert law. With respect to the placebo readings, we observed (1) significant increases in cerebral concentrations of oxidized CCO (Δ[CCO]; >0.08 µM; p 0.8 µM; p 0.5 µM; p < 0.01) during and after TILS, and (2) linear interplays between Δ[CCO] versus Δ[HbO] and between Δ[CCO] versus Δ[HbT]. Ratios of Δ[CCO]/Δ[HbO] and Δ[CCO]/Δ[HbT] were introduced as TILS-induced metabolic-hemodynamic coupling indices to quantify the coupling strength between TILS-enhanced cerebral metabolism and blood oxygen supply. This study provides the first demonstration that TILS causes up-regulation of oxidized CCO in the human brain, and contributes important insight into the physiological mechanisms.

Concept of infrared laser particle accelerators with oversized DBR and HFB waveguides

International Nuclear Information System (INIS)

Arnesson, J.; Gnepf, S.; Nessi, M.; Woelfli, W.; Kneubuehl, F.K.

1986-01-01

We present an infrared-laser accelerator scheme which makes use of hollow oversized linear periodic and helical waveguide structures originally designed for distributed feedback (DFB) and helical feedback (HFB) lasers

Near Infrared Photoimmunotherapy with Combined Exposure of External and Interstitial Light Sources.

Science.gov (United States)

Maruoka, Yasuhiro; Nagaya, Tadanobu; Sato, Kazuhide; Ogata, Fusa; Okuyama, Shuhei; Choyke, Peter L; Kobayashi, Hisataka

2018-02-21

Near infrared photoimmunotherapy (NIR-PIT) is a new target-cell-specific cancer treatment that induces highly selective necrotic/immunogenic cell death after systemic administration of a photoabsorber antibody conjugate and subsequent NIR light exposure. However, the depth of NIR light penetration in tissue (approximately 2 cm) with external light sources limits the therapeutic effects of NIR-PIT. Interstitial light exposure using cylindrical diffusing optical fibers can overcome this limitation. The purpose in this study was to compare three NIR light delivery methods for treating tumors with NIR-PIT using a NIR laser system at an identical light energy; external exposure alone, interstitial exposure alone, and the combination. Panitumumab conjugated with the photoabsorber IRDye-700DX (pan-IR700) was intravenously administered to mice with A431-luc xenografts which are epithelial growth factor receptor (EGFR) positive. One and 2 days later, NIR light was administered to the tumors using one of three methods. Interstitial exposure alone and in combination with external sources showed the greatest decrease in bioluminescence signal intensity. Additionally, the combination of external and interstitial NIR light exposure showed significantly greater tumor size reduction and prolonged survival after NIR-PIT compared to external exposure alone. This result suggested that the combination of external and interstitial NIR light exposure was more effective than externally applied light alone. Although external exposure is the least invasive means of delivering light, the combination of external and interstitial exposures produces superior therapeutic efficacy in tumors greater than 2 cm in depth from the tissue surface.

Comparison of laser-based mitigation of fused silica surface damage using mid- versus far-infrared lasers

Energy Technology Data Exchange (ETDEWEB)

Yang, S T; Matthews, M J; Elhadj, S; Cooke, D; Guss, G M; Draggoo, V G; Wegner, P J

2009-12-16

Laser induced growth of optical damage can limit component lifetime and therefore operating costs of large-aperture fusion-class laser systems. While far-infrared (IR) lasers have been used previously to treat laser damage on fused silica optics and render it benign, little is known about the effectiveness of less-absorbing mid-IR lasers for this purpose. In this study, they quantitatively compare the effectiveness and efficiency of mid-IR (4.6 {micro}m) versus far-IR (10.6 {micro}m) lasers in mitigating damage growth on fused silica surfaces. The non-linear volumetric heating due to mid-IR laser absorption is analyzed by solving the heat equation numerically, taking into account the temperature-dependent absorption coefficient {alpha}(T) at {lambda} = 4.6 {micro}m, while far-IR laser heating is well-described by a linear analytic approximation to the laser-driven temperature rise. In both cases, the predicted results agree well with surface temperature measurements based on infrared radiometry, as well as sub-surface fictive temperature measurements based on confocal Raman microscopy. Damage mitigation efficiency is assessed using a figure of merit (FOM) relating the crack healing depth to laser power required, under minimally-ablative conditions. Based on their FOM, they show that for cracks up to at least 500 {micro}m in depth, mitigation with a 4.6 {micro}m mid-IR laser is more efficient than mitigation with a 10.6 {micro}m far-IR laser. This conclusion is corroborated by direct application of each laser system to the mitigation of pulsed laser-induced damage possessing fractures up to 225 {micro}m in depth.

All-Quantum-Dot Infrared Light-Emitting Diodes

KAUST Repository

Yang, Zhenyu; Voznyy, Oleksandr; Liu, Mengxia; Yuan, Mingjian; Ip, Alexander H.; Ahmed, Osman S.; Levina, Larissa; Kinge, Sachin; Hoogland, Sjoerd; Sargent, Edward H.

2015-01-01

© 2015 American Chemical Society. Colloidal quantum dots (CQDs) are promising candidates for infrared electroluminescent devices. To date, CQD-based light-emitting diodes (LEDs) have employed a CQD emission layer sandwiched between carrier transport

Quantum cascade laser infrared spectroscopy of single cancer cells

KAUST Repository

Patel, Imran; Rajamanickam, Vijayakumar Palanisamy; Bertoncini, Andrea; Pagliari, Francesca; Tirinato, Luca; Laptenok, Sergey P.; Liberale, Carlo

2017-01-01

Quantum cascade laser infrared spectroscopy is a next generation novel imaging technique allowing high resolution spectral imaging of cells. We show after spectral pre-processing, identification of different cancer cell populations within minutes.

Quantum cascade laser infrared spectroscopy of single cancer cells

KAUST Repository

Patel, Imran

2017-03-27

Quantum cascade laser infrared spectroscopy is a next generation novel imaging technique allowing high resolution spectral imaging of cells. We show after spectral pre-processing, identification of different cancer cell populations within minutes.

Infrared temperature measurement and interference analysis of magnesium alloys in hybrid laser-TIG welding process

International Nuclear Information System (INIS)

Huang, R.-S.; Liu, L.-M.; Song, G.

2007-01-01

Infrared (IR) temperature measurement, as a convenient, non-contact method for making temperature field measurements, has been widely used in the fields of welding, but the problem of interference from radiant reflection is a complicating factor in applying IR temperature sensing to welding. The object of this research is to make a deep understand about the formation of interference, explore a new method to eliminate the interfering radiation during laser-TIG hybrid welding of magnesium alloys and to obtain the distribution of temperature field accurately. The experimental results showed that the interferences caused by radiant specular reflection of arc light, ceramic nozzle, electrode and laser nozzle were transferred out of welding seam while the IR thermography system was placed perpendicularly to welding seam. And the welding temperature distribution captured by IR termography system which had been calibrated by thermocouple was reliable by using this method in hybrid laser-TIG welding process of AZ31B magnesium alloy

Direct femtosecond laser writing of buried infrared waveguides in chalcogenide glasses

Science.gov (United States)

Le Coq, D.; Bychkov, E.; Masselin, P.

2016-02-01

Direct laser writing technique is now widely used in particular in glass, to produce both passive and active photonic devices. This technique offers a real scientific opportunity to generate three-dimensional optical components and since chalcogenide glasses possess transparency properties from the visible up to mid-infrared range, they are of great interest. Moreover, they also have high optical non-linearity and high photo-sensitivity that make easy the inscription of refractive index modification. The understanding of the fundamental and physical processes induced by the laser pulses is the key to well-control the laser writing and consequently to realize integrated photonic devices. In this paper, we will focus on two different ways allowing infrared buried waveguide to be obtained. The first part will be devoted to a very original writing process based on a helical translation of the sample through the laser beam. In the second part, we will report on another original method based on both a filamentation phenomenon and a point by point technique. Finally, we will demonstrate that these two writing techniques are suitable for the design of single mode waveguide for wavelength ranging from the visible up to the infrared but also to fabricate optical components.

Laser light scattering instrument advanced technology development

Science.gov (United States)

Wallace, J. F.

1993-01-01

The objective of this advanced technology development (ATD) project has been to provide sturdy, miniaturized laser light scattering (LLS) instrumentation for use in microgravity experiments. To do this, we assessed user requirements, explored the capabilities of existing and prospective laser light scattering hardware, and both coordinated and participated in the hardware and software advances needed for a flight hardware instrument. We have successfully breadboarded and evaluated an engineering version of a single-angle glove-box instrument which uses solid state detectors and lasers, along with fiber optics, for beam delivery and detection. Additionally, we have provided the specifications and written verification procedures necessary for procuring a miniature multi-angle LLS instrument which will be used by the flight hardware project which resulted from this work and from this project's interaction with the laser light scattering community.

Raman fiber lasers

CERN Document Server

2017-01-01

This book serves as a comprehensive, up-to-date reference about this cutting-edge laser technology and its many new and interesting developments. Various aspects and trends of Raman fiber lasers are described in detail by experts in their fields. Raman fiber lasers have progressed quickly in the past decade, and have emerged as a versatile laser technology for generating high power light sources covering a spectral range from visible to mid-infrared. The technology is already being applied in the fields of telecommunication, astronomy, cold atom physics, laser spectroscopy, environmental sensing, and laser medicine. This book covers various topics relating to Raman fiber laser research, including power scaling, cladding and diode pumping, cascade Raman shifting, single frequency operation and power amplification, mid-infrared laser generation, specialty optical fibers, and random distributed feedback Raman fiber lasers. The book will appeal to scientists, students, and technicians seeking to understand the re...

Mass Spectrometric Fingerprinting of Tank Waste Using Tunable, Ultrafast Infrared Lasers

International Nuclear Information System (INIS)

Richard Haglund Jr.

2002-01-01

The principal scientific thrust of this project was to demonstrate a novel method for precision matrix-assisted laser desorption-ionization (MALDI) mass spectrometry (MS) of model tank-waste materials using, using the sodium nitrate component of the tank waste both as the matrix and as an internal calibration standard. Conventional nanosecond and femtosecond single-frequency lasers and a tunable, mid-infrared free-electron laser were used in the development of the MS protocols and in measurements of the MALDI dynamics. In addition to developing a model of the processes which lead to efficient desorption and ionization of organic molecules (e.g., toluene, benzene, chelators, various organic acids, crown ethers) from sodium nitrate, we developed protocols for quantitative analysis based on the use of the sodium nitrate in tank waste as an internal standard. Comparisons of MALDI-MS using nanosecond and picosecond lasers, and of infrared and ultraviolet lasers, have been especially instructive, and demonstrate the superior potential of IR-MALDI for this purpose, as well as for a number of related analytical and thin-film applications

Laser warning receiver to identify the wavelength and angle of arrival of incident laser light

Science.gov (United States)

Sinclair; Michael B.; Sweatt, William C.

2010-03-23

A laser warning receiver is disclosed which has up to hundreds of individual optical channels each optically oriented to receive laser light from a different angle of arrival. Each optical channel has an optical wedge to define the angle of arrival, and a lens to focus the laser light onto a multi-wavelength photodetector for that channel. Each multi-wavelength photodetector has a number of semiconductor layers which are located in a multi-dielectric stack that concentrates the laser light into one of the semiconductor layers according to wavelength. An electrical signal from the multi-wavelength photodetector can be processed to determine both the angle of arrival and the wavelength of the laser light.

Slow-light effects in photonic crystal membrane lasers

DEFF Research Database (Denmark)

Xue, Weiqi; Yu, Yi; Ottaviano, Luisa

2015-01-01

In this paper, we present a systematic investigation of photonic crystal cavity laser operating in the slow-light regime. The dependence of lasing threshold on the effect of slow-light will be particularly highlighted.......In this paper, we present a systematic investigation of photonic crystal cavity laser operating in the slow-light regime. The dependence of lasing threshold on the effect of slow-light will be particularly highlighted....

Effects of laser radiation parameters of the infrared multiphoton dissociation of protonated trichloroethylene

International Nuclear Information System (INIS)

Ungureanu, C.; Almasan, V.

1994-01-01

The favorable properties of the infrared multiphoton absorption and dissociation of trichloroethylene-H, (C 2 HCl 3 ), by TEA-CO 2 laser radiation and rapid isotopic exchange between this molecule and water, indicate that it can be a promising further candidate for the final enrichment of heavy water (> 98% D 2 O), by laser method. We present the results obtained in the isotopic selectivity of multiphoton absorption measurements and in the study of the pulse energy and frequency laser radiation influence on the infrared multiphoton dissociation of C 2 HCl 3 in isotopic mixture with C 2 DCl 3 . (Author)

Integrative Multi-Spectral Sensor Device for Far-Infrared and Visible Light Fusion

Science.gov (United States)

Qiao, Tiezhu; Chen, Lulu; Pang, Yusong; Yan, Gaowei

2018-06-01

Infrared and visible light image fusion technology is a hot spot in the research of multi-sensor fusion technology in recent years. Existing infrared and visible light fusion technologies need to register before fusion because of using two cameras. However, the application effect of the registration technology has yet to be improved. Hence, a novel integrative multi-spectral sensor device is proposed for infrared and visible light fusion, and by using the beam splitter prism, the coaxial light incident from the same lens is projected to the infrared charge coupled device (CCD) and visible light CCD, respectively. In this paper, the imaging mechanism of the proposed sensor device is studied with the process of the signals acquisition and fusion. The simulation experiment, which involves the entire process of the optic system, signal acquisition, and signal fusion, is constructed based on imaging effect model. Additionally, the quality evaluation index is adopted to analyze the simulation result. The experimental results demonstrate that the proposed sensor device is effective and feasible.

Separation of nitrogen isotopes by laser light

Energy Technology Data Exchange (ETDEWEB)

Izawa, Y; Noguchi, Y; Yamanaka, C [Osaka Univ., Suita (Japan). Faculty of Engineering

1976-06-01

The separation experiment on nitrogen isotopes by laser light was made. First, the nitrogen isotopes of /sup 14/N and /sup 15/N in NH/sub 3/ molecules were separated by CO/sub 2/ laser and UV light. The separation factor and the enrichment factor were calculated. It was shown that their pressure dependence was in good agreement with the measured values. The separation factor of about 2% was obtained with UV light of 10/sup 6/W/cm/sup 2/.

Vibrational relaxation of CDCl3 induced by infrared laser radiation

International Nuclear Information System (INIS)

Alvarez, R.F.; Azcarate, M.L.; Alonso, E.M.; Dangelo, R.J.; Quel, E.J.

1990-01-01

A CO 2 TEA laser was used to excite mode ν 4 of CDCl 3 (914cm- 1 ). The laser was constructed at the laboratory, tuned in line 10P(48), (10.91 μm). Infrared fluorescence technique was used to determine V-T/R relaxation times for CDCl 3 both pure and in Ar mixtures. (Author). 9 refs., 3 figs

Highly efficient dual-wavelength mid-infrared CW Laser in diode end-pumped Er:SrF2 single crystals

Science.gov (United States)

Ma, Weiwei; Qian, Xiaobo; Wang, Jingya; Liu, Jingjing; Fan, Xiuwei; Liu, Jie; Su, Liangbi; Xu, Jun

2016-11-01

The spectral properties and laser performance of Er:SrF2 single crystals were investigated and compared with Er:CaF2. Er:SrF2 crystals have larger absorption cross-sections at the pumping wavelength, larger mid-infrared stimulated emission cross-sections and much longer fluorescence lifetimes of the upper laser level (Er3+:4I11/2 level) than those of Er:CaF2 crystals. Dual-wavelength continuous-wave (CW) lasers around 2.8 μm were demonstrated in both 4at.% and 10at.% Er:SrF2 single crystals under 972 nm laser diode (LD) end pumping. The laser wavelengths are 2789.3 nm and 2791.8 nm in the former, and 2786.4 nm and 2790.7 nm in the latter, respectively. The best laser performance has been demonstrated in lightly doped 4at.% Er:SrF2 with a low threshold of 0.100 W, a high slope efficiency of 22.0%, an maximum output power of 0.483 W.

Active mode locking of quantum cascade lasers in an external ring cavity.

Science.gov (United States)

Revin, D G; Hemingway, M; Wang, Y; Cockburn, J W; Belyanin, A

2016-05-05

Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode-locked operation remains a challenge, despite dedicated effort. Here we report the demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents.

A twin optically-pumped far-infrared CH3OH laser for plasma diagnostics

International Nuclear Information System (INIS)

Yamanaka, M.; Takeda, Y.; Tanigawa, S.; Nishizawa, A.; Noda, N.

1979-11-01

A twin optically-pumped far-infrared CH 3 OH laser has been constructed for use in plasma diagnostics. The anti-symmetric doublet due to the Raman-type resonant two-photon transition is reproducibly observed at 118.8 μm. With the 118.8-μm line, it is obtained from the frequency separation of the anti-symmetric doublet that the CH 3 OH absorption line center is 16 +- 1 MHz higher than the pump 9.7-μm P(36) CO 2 laser line center. It is shown that the Raman-type resonant two-photon transition is useful in order to get several-MHz phase modulation for the far-infrared laser interferometer. Some preliminary performances of this twin laser for the modulated interferometer are described. (author)

Laser light scattering basic principles and practice

CERN Document Server

Chu, Benjamin

1994-01-01

Geared toward upper-level undergraduate and graduate students, this text introduces the interdisciplinary area of laser light scattering, focusing chiefly on theoretical concepts of quasielastic laser scattering.

Infrared Supercontinuum Generation in Optical Fibres

DEFF Research Database (Denmark)

Dupont, Sune Vestergaard Lund

During my PhD studies I have worked with intense lasers and optical fibres. In our conceptual universe the colour of light (wavelength) does not depend on the material in which it propagates. At high intensities however, nonlinear effects change the behaviour of light and rise of new wavelength...... with laser-like intensity is obtained, which otherwise is impossible without the use of more complicated equipment. Until recently, supercontinuum covering the mid-infrared was not possible due to absorption in the silica glass optical fibres are made of. In our project infrared transparent materials...... such as ZBLAN and chalcogenide have been investigated. Using ZBLAN it has been possible to generated a supercontinuum stretching beyond 4200 nm. Supercontinuum generation requires knowledge about the physical properties of the optical fibre in which the pulse-broadening takes place. Consequently thorough...

1.9 W yellow, CW, high-brightness light from a high efficiency semiconductor laser-based system

DEFF Research Database (Denmark)

Hansen, Anders Kragh; Christensen, Mathias; Noordegraaf, Danny

2017-01-01

Semiconductor lasers are ideal sources for efficient electrical-to-optical power conversion and for many applications where their small size and potential for low cost are required to meet market demands. Yellow lasers find use in a variety of bio-related applications, such as photocoagulation......, imaging, flow cytometry, and cancer treatment. However, direct generation of yellow light from semiconductors with sufficient beam quality and power has so far eluded researchers. Meanwhile, tapered semiconductor lasers at near-infrared wavelengths have recently become able to provide neardiffraction...... power in just 60 seconds. An advantage of using a single pass configuration, rather than an external cavity configuration, is increased stability towards external perturbations. For example, stability to fluctuating case temperature over a 30 K temperature span has been demonstrated. The combination...

Comparative clinical study using laser and LED-therapy for orofacial pain relief: dentin hypersensitivity and cervicogenic headache

Science.gov (United States)

Lizarelli, Rosane F. Z.; Pizzo, Renata C. A.; Florez, Fernando L. E.; Grecco, Clovis; Speciali, Jose G.; Bagnato, Vanderlei S.

2015-06-01

Considering several clinical situations, low intensity laser therapy has been widely applied in pain relief or analgesia mechanism. With the advent of new LED-based (light emitting diode) light sources, the need of further clinical experiments aiming to compare the effectiveness among them is paramount. The LED system therapeutic use can be denominated as LEDT - Light Emitting Diode Therapy. This study proposed two clinical evaluations of pain relief effect: to dentin hypersensitivity and to cervicogenic headache using different sources of lasers (low and high intensity) and light emitting diodes (LEDs), one emitting at the spectral band of red (630+/- 5nm) and the other one at infrared band (880+/- 5nm). Two different clinical studies were performed and presented interesting results. Considering dentin hypersensitivity, red and infrared led were so effective than the control group (high intensity laser system); by the other side, considering cervicogenic headache, control group (infrared laser) was the best treatment in comparison to red and infrared led system.

Isotope separation by selective dissociation of trifluoromethane with an infrared laser

International Nuclear Information System (INIS)

Hartford, A.J.

1982-01-01

A process for obtaining compounds enriched in a desired isotope of an element selected from hydrogen and carbon comprises exposing subatmospheric pressure gaseous trifluoromethane containing said desired isotope and one or more other isotopes of the same element to infrared laser radiation of a predetermined frequency, which selectively dissociates trifluoromethane molecules containing said desired isotope and separating the resulting dissociation product enriched in said desired isotope from the remainder of the gas. The term 'trifluoromethane' (TFM) refers to a mixture of CF 3 H and CF 3 D, the latter constituting about 0.015 percent of the total. TFM is irradiated with a CO 2 laser at an appropriate infrared wavelength

Effect of laser-diode light on growth of Lactuca sativa L

International Nuclear Information System (INIS)

Yamazaki, A.; Tsuchiya, H.; Miyajima, H.; Honma, T.; Kan, H.

2000-01-01

Development of an effective, high-power, low-cost, artificial light source for use in plant-growing facilities would be very beneficial for plant production. Recently, the laser-diode lamp was proposed as a new type of light source for plant production. The advantages of the laser-diode lamp over conventional light sources are its high electrical-to-optical power conversion efficiency, low thermal radiation, easy set-up for high power and pulse irradiation, small weight and small volume for mounting, and selectivity for proper wavelength. Because laser light itself differs from the light sources presently used in plant growing, we confirmed the possibility of growing plants under the laser-diode light using lettuces. Lettuce seedlings with 5-6 leaves were grown under a laser-diode lamp panel with 30 pieces of high-power and high-efficiency AlGaInP laser-diodes. The power of each laser-diode lamp was 500 mW, and the wavelength was 680 nm, which was efficient for photosynthesis. The lettuce plants were able to grow under the laser-diode light. However, plants were lighter and had thinner leaves than those grown under high-pressure sodium lamps. (author)

Laser-induced plasma from pure and doped water-ice at high fluence by ultraviolet and infrared radiation - art. no. 70050X

DEFF Research Database (Denmark)

Schou, Jørgen; Matei, A.; Rodrigo, Katarzyna Agnieszka

2008-01-01

Ice made of ultrapure water or water doped with 1 % polymer (polyethylene glycol, "PEG") was irradiated by laser light with fluences between 2 and 80 J/cm(2) in the ultraviolet (UV) regime at 355 nm and in the infrared (IR) regime at 1064 nm in vacuum. In the UV regime there is a threshold for pl...... of ionization breakdown at the ice surface....

2 W high efficiency PbS mid-infrared surface emitting laser

Science.gov (United States)

Ishida, A.; Sugiyama, Y.; Isaji, Y.; Kodama, K.; Takano, Y.; Sakata, H.; Rahim, M.; Khiar, A.; Fill, M.; Felder, F.; Zogg, H.

2011-09-01

High efficiency laser operation with output power exceeding 2 W was obtained for vertical external-cavity PbS based IV-VI compound surface emitting quantum-well structures. The laser showed external quantum efficiency as high as 16%. Generally, mid-infrared III-V or II-VI semiconductor laser operation utilizing interband electron transitions are restricted by Auger recombination and free carrier absorption. Auger recombination is much lower in the IV-VI semiconductors, and the free-carrier absorption is significantly reduced by an optically pumped laser structure including multi-step optical excitation layers.

Evidence-based review of lasers, light sources and photodynamic therapy in the treatment of acne vulgaris

DEFF Research Database (Denmark)

Hædersdal, Merete; Togsverd-Bo, Katrine; Wulf, Hans Chr.

2008-01-01

through searches in PubMed and the Cochrane Library. Results A total of 16 randomized controlled trials (RCT) and 3 controlled trials (CT) were identified, involving a total of 587 patients. Interventions included photodynamic therapy (PDT; 5 RCTs), infrared lasers (4 RCTs), broad-spectrum light sources...... outcomes for PDT. We recommend that patients are preoperatively informed of the existing evidence, which indicates that optical treatments today are not included among first line treatments Udgivelsesdato: 2008/3...

Magnetic field generation by circularly polarized laser light and inertial plasma confinement in a miniature 'Magnetic Bottle' induced by circularly polarized laser light

International Nuclear Information System (INIS)

Kolka, E.

1993-07-01

A new concept of hot plasma confinement in a miniature magnetic bottle induced by circularly polarized laser light is suggested in this work. Magnetic fields generated by circularly polarized laser light may be of the order of megagauss. In this configuration the circularly polarized laser light is used to get confinement of a plasma contained in a good conductor vessel. The poloidal magnetic field induced by the circularly polarized laser and the efficiency of laser absorption by the plasma are calculated in this work. The confinement in this scheme is supported by the magnetic forces and the Lawson criterion for a DT plasma might be achieved for number density n=5*10 21 cm -3 and confinement time τ= 20 nsec. The laser and the plasma parameters required to get an energetic gain are calculated. (authors)

Near-infrared light emitting device using semiconductor nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Supran, Geoffrey J.S.; Song, Katherine W.; Hwang, Gyuweon; Correa, Raoul Emile; Shirasaki, Yasuhiro; Bawendi, Moungi G.; Bulovic, Vladimir; Scherer, Jennifer

2018-04-03

A near-infrared light emitting device can include semiconductor nanocrystals that emit at wavelengths beyond 1 .mu.m. The semiconductor nanocrystals can include a core and an overcoating on a surface of the core.

Supercontinuum light sources for food analysis

DEFF Research Database (Denmark)

Møller, Uffe Visbech; Petersen, Christian Rosenberg; Kubat, Irnis

2014-01-01

. One track of Light & Food will target the mid-infrared spectral region. To date, the limitations of mid-infraredlight sources, such as thermal emitters, low-power laser diodes, quantum cascade lasers and synchrotron radiation, have precluded mid-IR applications where the spatial coherence, broad...... bandwidth,high brightness and portability of a supercontinuum laser are all required. DTU Fotonik has now demonstrated the first optical fiber based broadband supercontinuum light souce, which covers 1.4-13.3μm and thereby most of the molecular fingerprint region....

Lasers, light-atom interaction

International Nuclear Information System (INIS)

Cagnac, B.; Faroux, J.P.

2002-01-01

This book has a double purpose: first to explain in a way as simple as possible the interaction processes occurring between atoms and light waves, and secondly to help any scientist that needs further information to improve his knowledge of lasers. The content of this book has been parted into 3 more or less independent sections: 1) effect of an electromagnetic field on a 2-quantum state system, 2) operating mode of lasers in the framework of transition probabilities, and 3) calculation of the emitted wave. Einstein's phenomenological hypothesis has led to probability equations called rate equations, these equations do not give a true representation of the interaction process at the scale of the atom but this representation appears to be true on an average over a large population of atoms. Only quantum mechanics can describe accurately the light-atom interaction but at the cost of a far higher complexity. In the first part of the book quantum mechanics is introduced and applied under 2 simplifying hypothesis: -) the atom system has only 2 non-degenerate states and -) the intensity of the light wave is high enough to involve a large population of photons. Under these hypothesis, Rabi oscillations, Ramsey pattern and the splitting of Autler-Townes levels are explained. The second part is dedicated to the phenomenological model of Einstein that gives good results collectively. In the third part of the book, Maxwell equations are used to compute field spatial distribution that are currently found in experiments involving lasers. (A.C.)

LIGHT: Towards a laser-based accelerator

Energy Technology Data Exchange (ETDEWEB)

Busold, Simon; Deppert, Oliver; Roth, Markus [Technical University of Darmstadt, Institute for Nuclear Physics, Schlossgartenstrasse 9, 64289 Darmstadt (Germany); Brabetz, Christian [Goethe University Frankfurt am Main, Institute for Applied Physics, Max von Laue Strasse 1, 60438 Frankfurt (Germany); Burris-Mog, Trevor; Joost, Martin; Cowan, Tom [Helmholtz Center Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden (Germany); Blazevic, Abel; Bagnoud, Vincent [GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt (Germany); Zielbauer, Bernhard [GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt (Germany); Helmholtz Institute Jena, Helmholtzweg 4, 07743 Jena (Germany); Kester, Oliver [GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt (Germany); Goethe University Frankfurt am Main, Institute for Applied Physics, Max von Laue Strasse 1, 60438 Frankfurt (Germany)

2012-07-01

Proton acceleration by ultrashort, high intensity laser pulses has been a fast growing field of research during the last decade. The most intensely investigated acceleration mechanism is the TNSA mechanism (Target Normal Sheath Acceleration), providing protons in the multi-MeV-range. For many possible applications, however, the full energy spread and large beam divergence are major draw-backs. Therefore, a pulsed high-field solenoid was used for collimation and energy-selection and is now integrated in a full test stand for a laser-based accelerator at GSI Helmholtz Center, Darmstadt, namely the LIGHT project (Laser Ion Generation, Handling and Transport), which is a collaboration between TU Darmstadt, GSI, HZDR, JWGU Frankfurt and HI Jena. An overview of the new infrastructure, the goals of the LIGHT project, and first experimental results are presented.

Visible Lasers and Emerging Color Converters for Lighting and Visible Light Communications

KAUST Repository

Shen, Chao

2017-10-30

GaN-based lasers are promising for white lighting and visible-light communication (VLC). The advances of III-nitride photonic integration, and the application of YAG crystal and perovskite-based phosphors to lighting and VLC will be discussed.

Visible Lasers and Emerging Color Converters for Lighting and Visible Light Communications

KAUST Repository

Shen, Chao

2017-01-01

GaN-based lasers are promising for white lighting and visible-light communication (VLC). The advances of III-nitride photonic integration, and the application of YAG crystal and perovskite-based phosphors to lighting and VLC will be discussed.

Femtosecond laser irradiation-induced infrared absorption on silicon surfaces

Directory of Open Access Journals (Sweden)

Qinghua Zhu

2015-04-01

Full Text Available The near-infrared (NIR absorption below band gap energy of crystalline silicon is significantly increased after the silicon is irradiated with femtosecond laser pulses at a simple experimental condition. The absorption increase in the NIR range primarily depends on the femtosecond laser pulse energy, pulse number, and pulse duration. The Raman spectroscopy analysis shows that after the laser irradiation, the silicon surface consists of silicon nanostructure and amorphous silicon. The femtosecond laser irradiation leads to the formation of a composite of nanocrystalline, amorphous, and the crystal silicon substrate surface with microstructures. The composite has an optical absorption enhancement at visible wavelengths as well as at NIR wavelength. The composite may be useful for an NIR detector, for example, for gas sensing because of its large surface area.

Mid-infrared, long wave infrared (4-12 μm) molecular emission signatures from pharmaceuticals using laser-induced breakdown spectroscopy (LIBS).

Science.gov (United States)

Yang, Clayton S-C; Brown, Ei E; Kumi-Barimah, Eric; Hommerich, Uwe H; Jin, Feng; Trivedi, Sudhir B; Samuels, Alan C; Snyder, A Peter

2014-01-01

In an effort to augment the atomic emission spectra of conventional laser-induced breakdown spectroscopy (LIBS) and to provide an increase in selectivity, mid-wave to long-wave infrared (IR), LIBS studies were performed on several organic pharmaceuticals. Laser-induced breakdown spectroscopy signature molecular emissions of target organic compounds are observed for the first time in the IR fingerprint spectral region between 4-12 μm. The IR emission spectra of select organic pharmaceuticals closely correlate with their respective standard Fourier transform infrared spectra. Intact and/or fragment sample molecular species evidently survive the LIBS event. The combination of atomic emission signatures derived from conventional ultraviolet-visible-near-infrared LIBS with fingerprints of intact molecular entities determined from IR LIBS promises to be a powerful tool for chemical detection.

Mid-infrared pulsed laser ultrasonic testing for carbon fiber reinforced plastics.

Science.gov (United States)

Kusano, Masahiro; Hatano, Hideki; Watanabe, Makoto; Takekawa, Shunji; Yamawaki, Hisashi; Oguchi, Kanae; Enoki, Manabu

2018-03-01

Laser ultrasonic testing (LUT) can realize contactless and instantaneous non-destructive testing, but its signal-to-noise ratio must be improved in order to measure carbon fiber reinforced plastics (CFRPs). We have developed a mid-infrared (mid-IR) laser source optimal for generating ultrasonic waves in CFRPs by using a wavelength conversion device based on an optical parametric oscillator. This paper reports a comparison of the ultrasonic generation behavior between the mid-IR laser and the Nd:YAG laser. The mid-IR laser generated a significantly larger ultrasonic amplitude in CFRP laminates than a conventional Nd:YAG laser. In addition, our study revealed that the surface epoxy matrix of CFRPs plays an important role in laser ultrasonic generation. Copyright © 2017 Elsevier B.V. All rights reserved.

[Light, laser and PDT therapy for acne].

Science.gov (United States)

Borelli, C; Merk, K; Plewig, G; Degitz, K

2005-11-01

In recent years, a number of studies have evaluated the treatment of acne using electromagnetic waves, such as lasers, photodynamic therapy, visible light or radio waves. While the efficacy of laser treatment is still uncertain, photodynamic therapy shows promising results, but with marked side-effects, as destruction of sebaceous glands. Treatment with blue light (405-420 nm wavelength) also appears effective and can be regarded as an treatment option for inflammatory acne.

Laser-Induced Breakdown Spectroscopy Infrared Emission From Inorganic and Organic Substances

National Research Council Canada - National Science Library

Yang, C.S; Brown, E; Hommerich, U; Trivedi, S. B; Snyder, A. P; Samuels, A. C

2006-01-01

.... The ultraviolet-visible-near infrared (UV-Vis- NIR) spectral region exploited in conventional LIBS largely elucidates the elemental composition of the laser target by profiling these atomic lines...

Self-phase modulation of laser light in laser produced plasma

International Nuclear Information System (INIS)

Yamanaka, C.; Yamanaka, T.; Mizui, J.; Yamaguchi, N.

1975-02-01

A spectrum broadening due to the self-phase modulation of a laser light was observed in the laser produced deuterium and hydrogen plasma. Qualitative treatments of the density modulation due to the self-focusing process and the modulational instability were discussed. The theoretical estimation of spectrum broadening fairly accorded with the experimental results. (auth.)

Optical laser systems at the Linac Coherent Light Source

Energy Technology Data Exchange (ETDEWEB)

Minitti, Michael P.; Robinson, Joseph S.; Coffee, Ryan N.; Edstrom, Steve; Gilevich, Sasha; Glownia, James M.; Granados, Eduardo; Hering, Philippe; Hoffmann, Matthias C.; Miahnahri, Alan; Milathianaki, Despina; Polzin, Wayne; Ratner, Daniel; Tavella, Franz; Vetter, Sharon; Welch, Marc; White, William E.; Fry, Alan R., E-mail: alanfry@slac.stanford.edu [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

2015-04-22

This manuscript serves as a reference to describe the optical laser sources and capabilities at the Linac Coherent Light Source. Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump–probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump–probe experiments to be performed at LCLS.

Supercontinuum: broad as a lamp, bright as a laser, now in the mid-infrared

Science.gov (United States)

Moselund, Peter M.; Petersen, Christian; Dupont, Sune; Agger, Christian; Bang, Ole; Keiding, Søren R.

2012-06-01

Based on the experience gained developing our market leading visible spectrum supercontinuum sources NKT Photonics has built the first mid-infrared supercontinuum source based on modelocked picosecond fiber lasers. The source is pumped by a ~ 2 um laser based on a combination of erbium and thulium and use ZBLAN fibers to generate a 1.75-4.4 μm spectrum. We will present results obtained by applying the source for mid-infrared microscopy where absorption spectra can be used to identify the chemical nature of different parts of a sample. Subsequently, we discuss the possible application of a mid-IR supercontinuum source in other areas including infrared countermeasures.

A thyratron-switched modular CO2 TEA laser for infrared photochemical studies

International Nuclear Information System (INIS)

Hamilton, N.; Kelly, J.W.; Struve, H.

1982-09-01

A thyratron-switched, ultraviolet pre-ionised CO 2 TEA laser, consisting of four modules connected in series, has been designed and constructed. The laser can be operated in the TEM 00 mode and is able to produce 2.5 J per pulse. The design and operation of the laser as a tool for infrared studies is discussed together with an evaluation of the effect of operating parameters on output characteristics

Light-material interactions in laser material processing

International Nuclear Information System (INIS)

Chiang, S.; Albright, C.E.

1989-01-01

The authors discusses how light interactions with materials in laser material processing operations occur by a variety of mechanisms depending on the material being processed, the wavelength of the laser light, the gaseous environment, and the physical state of the material surface. The high reflectivity of metals limits the fraction of the beam power absorbed by the solid metal surface. For metals in the solid state, reflectivity increases as the wavelength of the laser light and the electrical conductivity of the metal increase. The reflectivity of metals is reduced upon heating to the melting point, and further reduced upon melting. At high power densities the liquid metal surface is heated so quickly that very rapid vaporization occurs. The recoil force produced by the evaporation causes a depression in the liquid/vapor interface. The keyhole resulting from this depression allows for multiple reflections and thus increases beam absorption in the liquid

Laser driven white light source for BRDF measurement

DEFF Research Database (Denmark)

Amdemeskel, Mekbib Wubishet; Thorseth, Anders; Dam-Hansen, Carsten

2017-01-01

In this paper, we will present a setup with laser driven light source (LDLS) for measuring a 2D bidirectional reflectance distribution function (BRDF). We have carried out measurements to acquire the BRDF of different samples based on our setup: which consists of a new laser driven broadband light...... source (UV-VIS-NIR), spectroradiometer and sample holder stepper motor in a dark UV-protected environment. Here, we introduced a special kind of light source which has a bright, stable, broad spectral range and well collimated light output to give a very good angular resolution. The experimental results...

Cell viability, reactive oxygen species, apoptosis, and necrosis in myoblast cultures exposed to low-level infrared laser.

Science.gov (United States)

Alexsandra da Silva Neto Trajano, Larissa; da Silva, Camila Luna; de Carvalho, Simone Nunes; Cortez, Erika; Mencalha, André Luiz; de Souza da Fonseca, Adenilson; Stumbo, Ana Carolina

2016-07-01

Low-level infrared laser is considered safe and effective for treatment of muscle injuries. However, the mechanism involved on beneficial effects of laser therapy are not understood. The aim was to evaluate cell viability, reactive oxygen species, apoptosis, and necrosis in myoblast cultures exposed to low-level infrared laser at therapeutic fluences. C2C12 myoblast cultures at different (2 and 10 %) fetal bovine serum (FBS) concentrations were exposed to low-level infrared laser (808 nm, 100 mW) at different fluences (10, 35, and 70 J/cm(2)) and evaluated after 24, 48, and 72 h. Cell viability was evaluated by WST-1 assay; reactive oxygen species (ROS), apoptosis, and necrosis were evaluated by flow cytometry. Cell viability was decreased atthe lowest FBS concentration. Laser exposure increased the cell viability in myoblast cultures at 2 % FBS after 48 and 72 h, but no significant increase in ROS was observed. Apoptosis was decreased at the higher fluence and necrosis was increased at lower fluence in myoblast cultures after 24 h of laser exposure at 2 % FBS. No laser-induced alterations were obtained at 10 % FBS. Results show that level of reactive oxygen species is not altered, at least to those evaluated in this study, but low-level infrared laser exposure affects cell viability, apoptosis, and necrosis in myoblast cultures depending on laser fluence and physiologic conditions of cells.

New lasers and light sources - old and new risks?

DEFF Research Database (Denmark)

Paasch, Uwe; Schwandt, Antje; Seeber, Nikolaus

2017-01-01

Recent developments (new wavelengths, treatment concepts, and combinations) in the field of lasers, intense pulsed light (IPL), LED, as well as new energy and light sources have opened up new therapeutic options that extend beyond mere aesthetic indications. Thus, while fractional lasers used...

Development laser light facility for uranium isotope separation

International Nuclear Information System (INIS)

Dickinson, G.J.

1992-01-01

A laser light facility has been built and successfully commissioned as part of a programme to explore the economic potential of Laser Isotope Separation of Uranium. The laser systems are comprised of tunable dye lasers pumped by copper vapour lasers. The requirements for optical beam stability, alignment of lasers in chains, and protection of optical coatings have made challenging demands on the engineering design and operation of the facility. (Author)

Killing Cancer Cells with the Help of Infrared Light – Photoimmunotherapy

Science.gov (United States)

Near-infrared photoimmunotherapy uses an antibody–photoabsorber conjugate that binds to cancer cells. When near-infrared light is applied, the cells swell and then burst, causing the cancer cell to die. Photoimmunotherapy is in clinical trials in patients with inoperable tumors.

Hypericin and pulsed laser therapy of squamous cell cancer in vitro.

Science.gov (United States)

Bublik, Michael; Head, Christian; Benharash, Peyman; Paiva, Marcos; Eshraghi, Adrian; Kim, Taiho; Saxton, Romaine

2006-06-01

This in vitro study compares continuous wave and pulsed laser light at longer wavelengths for activation of the phototoxic drug hypericin in human cancer cells. Two-photon pulsed laser light now allows high-resolution fluorescent imaging of cancer cells and should provide deeper tissue penetration with near infrared light for improved detection as well as phototoxicity in human tumors. Cultured Seoul National University (SNU)-1 tumor cells from a squamous cell carcinoma (SCC) were incubated with hypericin before photoirradiation at four laser wavelengths. Phototoxicity of hypericin sensitized SCC cells was measured by dimethyl thiazoldiphenyl (MTT) tetrazolium bromide cell viability assays and by confocal fluorescence microscopy via 532-nm and infrared two-photon pulsed laser light. Phototoxic response increased linearly with hypericin dose of 0.1-2 microM, light exposure time of 5-120 sec, and pulsed dye laser wavelengths of 514-593 nm. Light energy delivery for 50% cell phototoxicity (LD50) response was 9 joules at 514 nm, 3 joules at 550 nm, and less than 1 joule at the 593 nm hypericin light absorption maxima. Fluorescence confocal microscopy revealed membrane and perinuclear localization of hypericin in the SNU cells with membrane damage seen after excitation with visible 532 nm continuous wave light or two-photon 700-950 nm picosecond pulsed laser irradiation. Hypericin may be a powerful tumor targetting drug when combined with pulsed laser light in patients with recurrent head and neck SCC.

New lasers and light sources - old and new risks?

DEFF Research Database (Denmark)

Paasch, Uwe; Schwandt, Antje; Seeber, Nikolaus

2017-01-01

Recent developments (new wavelengths, treatment concepts, and combinations) in the field of lasers, intense pulsed light (IPL), LED, as well as new energy and light sources have opened up new therapeutic options that extend beyond mere aesthetic indications. Thus, while fractional lasers used to ...

Ultrasensitive Detection of Infrared Photon Using Microcantilever: Theoretical Analysis

International Nuclear Information System (INIS)

Li-Xin, Cao; Feng-Xin, Zhang; Yin-Fang, Zhu; Jin-Ling, Yang

2010-01-01

We present a new method for detecting near-infrared, mid-infrared, and far-infrared photons with an ultrahigh sensitivity. The infrared photon detection was carried out by monitoring the displacement change of a vibrating microcantilever under light pressure using a laser Doppler vibrometer. Ultrathin silicon cantilevers with high sensitivity were produced using micro/nano-fabrication technology. The photon detection system was set up. The response of the microcantilever to the photon illumination is theoretically estimated, and a nanowatt resolution for the infrared photon detection is expected at room temperature with this method

Broadband mid-infrared superlattice light-emitting diodes

Science.gov (United States)

Ricker, R. J.; Provence, S. R.; Norton, D. T.; Boggess, T. F.; Prineas, J. P.

2017-05-01

InAs/GaSb type-II superlattice light-emitting diodes were fabricated to form a device that provides emission over the entire 3-5 μm mid-infrared transmission window. Variable bandgap emission regions were coupled together using tunnel junctions to emit at peak wavelengths of 3.3 μm, 3.5 μm, 3.7 μm, 3.9 μm, 4.1 μm, 4.4 μm, 4.7 μm, and 5.0 μm. Cascading the structure recycles the electrons in each emission region to emit several wavelengths simultaneously. At high current densities, the light-emitting diode spectra broadened into a continuous, broadband spectrum that covered the entire mid-infrared band. When cooled to 77 K, radiances of over 1 W/cm2 sr were achieved, demonstrating apparent temperatures above 1000 K over the 3-5 μm band. InAs/GaSb type-II superlattices are capable of emitting from 3 μm to 30 μm, and the device design can be expanded to include longer emission wavelengths.

NASA Laser Light Scattering Advanced Technology Development Workshop, 1988

Science.gov (United States)

Meyer, William V. (Editor)

1989-01-01

The major objective of the workshop was to explore the capabilities of existing and prospective laser light scattering hardware and to assess user requirements and needs for a laser light scattering instrument in a reduced gravity environment. The workshop addressed experimental needs and stressed hardware development.

Towards diode-pumped mid-infrared praseodymium-ytterbium-doped fluoride fiber lasers

Science.gov (United States)

Woodward, R. I.; Hudson, D. D.; Jackson, S. D.

2018-02-01

We explore the potential of a new mid-infrared laser transition in praseodymium-doped fluoride fiber for emission around 3.4 μm, which can be conveniently pumped by 0.975 μm diodes via ytterbium sensitizer co-doping. Optimal cavity designs are determined through spectroscopic measurements and numerical modeling, suggesting that practical diode-pumped watt-level mid-infrared fiber sources beyond 3 μm could be achieved.

DNA repair in bacterial cultures and plasmid DNA exposed to infrared laser for treatment of pain

International Nuclear Information System (INIS)

Canuto, K S; Sergio, L P S; Marciano, R S; Guimarães, O R; Polignano, G A C; Geller, M; Fonseca, A S; Paoli, F

2013-01-01

Biostimulation of tissues by low intensity lasers has been described on a photobiological basis and clinical protocols are recommended for treatment of various diseases, but their effects on DNA are controversial. The objective of this work was to evaluate effects of low intensity infrared laser exposure on survival and bacterial filamentation in Escherichia coli cultures, and induction of DNA lesions in bacterial plasmids. In E. coli cultures and plasmids exposed to an infrared laser at fluences used to treat pain, bacterial survival and filamentation and DNA lesions in plasmids were evaluated by electrophoretic profile. Data indicate that the infrared laser (i) increases survival of E. coli wild type in 24 h of stationary growth phase, (ii) induces bacterial filamentation, (iii) does not alter topological forms of plasmids and (iv) does not alter the electrophoretic profile of plasmids incubated with exonuclease III or formamidopyrimidine DNA glycosylase. A low intensity infrared laser at the therapeutic fluences used to treat pain can alter survival of E. coli wild type, induce filamentation in bacterial cells, depending on physiologic conditions and DNA repair, and induce DNA lesions other than single or double DNA strand breaks or alkali-labile sites, which are not targeted by exonuclease III or formamidopyrimidine DNA glycosylase. (letter)

Freedom from band-gap slavery: from diode lasers to quantum cascade lasers

Science.gov (United States)

Capasso, Federico

2010-02-01

Semiconductor heterostructure lasers, for which Alferov and Kromer received part of the Nobel Prize in Physics in 2000, are the workhorse of technologies such as optical communications, optical recording, supermarket scanners, laser printers and fax machines. They exhibit high performance in the visible and near infrared and rely for their operation on electrons and holes emitting photons across the semiconductor bandgap. This mechanism turns into a curse at longer wavelengths (mid-infrared) because as the bandgap, shrinks laser operation becomes much more sensitive to temperature, material defects and processing. Quantum Cascade Laser (QCL), invented in 1994, rely on a radically different process for light emission. QCLs are unipolar devices in which electrons undergo transitions between quantum well energy levels and are recycled through many stages emitting a cascade of photons. Thus by suitable tailoring of the layers' thickness, using the same heterostructure material, they can lase across the molecular fingerprint region from 3 to 25 microns and beyond into the far-infrared and submillimiter wave spectrum. High power cw room temperature QCLs and QCLs with large continuous single mode tuning range have found many applications (infrared countermeasures, spectroscopy, trace gas analysis and atmospheric chemistry) and are commercially available. )

Effects of infrared lasers on chemical extraction reactions in liquid-liquid systems

International Nuclear Information System (INIS)

Baoyu, X.

A study was made of the effects of infrared lasers on equilibrium distributions of uranyl ions between aqueous solution phases containing nitric acid or hydrochloric acid and organic solvent phases of tributyl phosphate (TBP). The experimental results indicated that uranium concentrations in the organic solvent phase increased under TEA CO 2 laser irradiation up to a maximum of 44% as compared to cases in which laser radiation was not applied. The possibility that this type of laser extraction effect might be applied to separation of uranium isotopes was also discussed

A Stark-tuned, far-infrared laser for high frequency plasma diagnostics

International Nuclear Information System (INIS)

Mansfield, D.K.; Vocaturo, M.; Guttadora, L.; Rockmore, M.; Micai, K.; Krug, P.A.

1992-03-01

A Stark-tuned optically pumped far-infrared methanol laser operating at 119 micrometers has been built. The laser is designed to operate at high power while exhibiting a well-separated Stark doublet. At a pump power of 65 Watts and electric field of 1 kV/cm the laser has delivered over 100 mW c.w. while exhibiting a frequency splitting of 34 MHz. These parameters indicate that this laser would be suitable for use in the present generation of modulated interferometers on large thermonuclear plasma devices. The achieved modulation frequency is more than an order of magnitude higher than could be achieved using standard techniques

Theoretical interpretations of enhanced laser light absorption

International Nuclear Information System (INIS)

Kruer, W.L.

1975-01-01

Intense laser light is not efficiently absorbed classically but can be absorbed by its conversion to electron plasma waves near the critical density. The physical mechanisms for this conversion are discussed, and some simple estimates for heating by plasma waves are applied to some recent experiments. Several effects which strongly influence the absorption of high intensity light are emphasized, including a nonlinear steepening of the plasma density profile which is demonstrated in computer simulations. Finally the possibility of an induced reflection of laser light due to instabilities in the underdense plasma before the critical density is also discussed. Such stimulated reflection can be particularly important in plasmas with very long density gradients. (U.S.)

How to harvest efficient laser from solar light

Science.gov (United States)

Zhao, Changming; Guan, Zhe; Zhang, Haiyang

2018-02-01

Solar Pumped Solid State Lasers (SPSSL) is a kind of solid state lasers that can transform solar light into laser directly, with the advantages of least energy transform procedure, higher energy transform efficiency, simpler structure, higher reliability, and longer lifetime, which is suitable for use in unmanned space system, for solar light is the only form of energy source in space. In order to increase the output power and improve the efficiency of SPSSL, we conducted intensive studies on the suitable laser material selection for solar pump, high efficiency/large aperture focusing optical system, the optimization of concave cavity as the second focusing system, laser material bonding and surface processing. Using bonded and grooved Nd:YAG rod as laser material, large aperture Fresnel lens as the first stage focusing element, concave cavity as the second stage focusing element, we finally got 32.1W/m2 collection efficiency, which is the highest collection efficiency in the world up to now.

Growth of micro-crystals in solution by in-situ heating via continuous wave infrared laser light and an absorber

Science.gov (United States)

Pathak, Shashank; Dharmadhikari, Jayashree A.; Thamizhavel, A.; Mathur, Deepak; Dharmadhikari, Aditya K.

2016-01-01

We report on growth of micro-crystals such as sodium chloride (NaCl), copper sulphate (CuSO4), potassium di-hydrogen phosphate (KDP) and glycine (NH2CH2COOH) in solution by in-situ heating using continuous wave Nd:YVO4 laser light. Crystals are grown by adding single walled carbon nanotubes (SWNT). The SWNTs absorb 1064 nm light and act as an in-situ heat source that vaporizes the solvent producing microcrystals. The temporal dynamics of micro-crystal growth is investigated by varying experimental parameters such as SWNT bundle size and incident laser power. We also report crystal growth without SWNT in an absorbing medium: copper sulphate in water. Even though the growth dynamics with SWNT and copper sulphate are significantly different, our results indicate that bubble formation is necessary for nucleation. Our simple method may open up new vistas for rapid growth of seed crystals especially for examining the crystallizability of inorganic and organic materials.

Evaluation of light detector surface area for functional Near Infrared Spectroscopy.

Science.gov (United States)

Wang, Lei; Ayaz, Hasan; Izzetoglu, Meltem; Onaral, Banu

2017-10-01

Functional Near Infrared Spectroscopy (fNIRS) is an emerging neuroimaging technique that utilizes near infrared light to detect cortical concentration changes of oxy-hemoglobin and deoxy-hemoglobin non-invasively. Using light sources and detectors over the scalp, multi-wavelength light intensities are recorded as time series and converted to concentration changes of hemoglobin via modified Beer-Lambert law. Here, we describe a potential source for systematic error in the calculation of hemoglobin changes and light intensity measurements. Previous system characterization and analysis studies looked into various fNIRS parameters such as type of light source, number and selection of wavelengths, distance between light source and detector. In this study, we have analyzed the contribution of light detector surface area to the overall outcome. Results from Monte Carlo based digital phantoms indicated that selection of detector area is a critical system parameter in minimizing the error in concentration calculations. The findings here can guide the design of future fNIRS sensors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Near-infrared light-controlled tunable grating based on graphene/elastomer composites

Science.gov (United States)

Wang, Fei; Jia, Shuhai; Wang, Yonglin; Tang, Zhenhua

2018-02-01

A near-infrared (nIR) light actuated tunable transmission optical grating based on graphene nanoplatelet (GNP)/polydimethylsiloxane (PDMS) and PDMS is proposed. A simple fabrication protocol is studied that allows integration of the grating with the actuation mechanism; both components are made from soft elastomers, and this ensure the tunability and the light-driven operation of the grating. The resulting grating structure demonstrates continuous period tunability of 2.7% under an actuation power density of 220 mW cm-2 within a period of 3 s and also demonstrates a time-independent characteristic. The proposed infrared activated grating can be developed for wireless remote light splitting in bio/chemical sensing and optical telecommunications applications.

Ferroelectric domain engineering by focused infrared femtosecond pulses

Energy Technology Data Exchange (ETDEWEB)

Chen, Xin; Shvedov, Vladlen; Sheng, Yan, E-mail: yan.sheng@anu.edu.au [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Karpinski, Pawel [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Wroclaw University of Technology, Wybrzeze Wyspianskiego, Wroclaw (Poland); Koynov, Kaloian [Max-Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany); Wang, Bingxia; Trull, Jose; Cojocaru, Crina [Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Rambla Sant Nebridi, 08222 Terrassa, Barcelona (Spain); Krolikowski, Wieslaw [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Texas A& M University at Qatar, Doha (Qatar)

2015-10-05

We demonstrate infrared femtosecond laser-induced inversion of ferroelectric domains. This process can be realised solely by using tightly focused laser pulses without application of any electric field prior to, in conjunction with, or subsequent to the laser irradiation. As most ferroelectric crystals like LiNbO{sub 3}, LiTaO{sub 3}, and KTiOPO{sub 4} are transparent in the infrared, this optical poling method allows one to form ferroelectric domain patterns much deeper inside a ferroelectric crystal than by using ultraviolet light and hence can be used to fabricate practical devices. We also propose in situ diagnostics of the ferroelectric domain inversion process by monitoring the Čerenkov second harmonic signal, which is sensitive to the appearance of ferroelectric domain walls.

Photoacoustic determination of glucose concentration in whole blood by a near-infrared laser diode

Science.gov (United States)

Zhao, Zuomin; Myllylae, Risto A.

2001-06-01

The near-infrared photoacoustic technique is recognized as a potential method for the non-invasive determination of human glucose, because near-infrared light can incident a few millimeters into human tissue, where it produces an acoustic wave capable of carrying information about the composition of the tissue. This paper demonstrates a photoacoustic glucose measurement in a blood sample as a step toward a non-invasive measurement. The experimental apparatus consists of a near-infrared laser diode operating with 4 micro joules pulse energy at 905 nm, a roller pump connected to a silicon plastic tube and a cuvette for circulating the blood sample. In addition, the apparatus comprises a PZT piezoelectric transducer integrated with a battery-powered preamplifier to receive the photoacoustic signal. During the experiment, a glucose solution is mixed into a human blood sample to change its concentration. Although the absorption coefficient of glucose is much smaller than that of blood in the near-infrared region, the osmotic and hydrophilic properties of glucose decrease the reduced scattering coefficient of blood caused by the dissolved glucose surrounding the blood cells. This changes the distribution of the absorbed optical energy in blood, which, in turn, produces a change in the photoacoustic signal. Our experiment demonstrates that signal amplitudes in fresh and stored blood samples in crease about 7% and 10%, respectively, when the glucose concentration reaches the upper limit of the physiological region (500 mg/dl).

Spot fat reduction by red and near infrared LED phototherapy

Science.gov (United States)

Lim, Sungkyoo; Park, Eal-Whan

2018-02-01

Low level light therapy (LLLT) using light from red and near infrared LEDs or Lasers have been reported effective as noninvasive methods for reducing spot fat. A total of 55 subjects were randomly divided into test groups and control groups for abdominal fat reduction clinical trial using red and near infrared LED phototherapy devices. Red and near infrared light with irradiance of 10 mW/cm2 were irradiated over the abdominal area to the test group for 30 minutes followed by 30 minutes of aerobic exercise, 3 times a week for 4 weeks. Control group used sham devices for 30 minutes and followed by 30 minutes of aerobic exercise. It is expected that red and near infrared LED phototherapy combined with aerobic exercise would be effective and safe for abdominal fat reduction without any side effects.

Infrared Laser Ablation with Vacuum Capture for Fingermark Sampling

Science.gov (United States)

Donnarumma, Fabrizio; Camp, Eden E.; Cao, Fan; Murray, Kermit K.

2017-09-01

Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonstrated on glass, plastic, aluminum, and cardboard surfaces. Using matrix assisted laser desorption ionization (MALDI), it was possible to detect caffeine after spiking with amounts as low as 1 ng. MALDI detection of condom lubricants and detection of antibacterial peptides from an antiseptic cream was demonstrated. Detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface using gas chromatography mass spectrometry (GC-MS) was shown. [Figure not available: see fulltext.

Collective laser light scattering from electron density fluctuations in fusion research plasmas (invited)

International Nuclear Information System (INIS)

Holzhauer, E.; Dodel, G.

1990-01-01

In magnetically confined plasmas density fluctuations of apparently turbulent nature with broad spectra in wave number and frequency space are observed which are thought to be the cause for anomalous energy and particle transport across the confining magnetic field. Collective laser light scattering has been used to study the nature of these fluctuations. Specific problems of scattering from fusion plasmas are addressed and illustrated with experimental results from the 119 μm far infrared laser scattering experiment operated on the ASDEX tokamak. Using the system in the heterodyne mode the direction of propagation with respect to the laboratory frame can be determined. Spatial resolution has bean improved by making use of the change in pitch of the total magnetic field across the minor plasma radius. Special emphasis is placed on the ohmic phase where a number of parameter variations including electron density, electron temperature, toroidal magnetic field, and filling gas were performed

A Low-Energy-Spread Rf Accelerator for a Far-Infrared Free-Electron Laser

NARCIS (Netherlands)

van der Geer, C. A. J.; Bakker, R. J.; van der Meer, A. F. G.; van Amersfoort, P. W.; Gillespie, W. A.; Saxon, G.; Poole, M. W.

1993-01-01

A high electron current and a small energy spread are essential for the operation of a free electron laser (FEL). In this paper we discuss the design and performance of the accelerator for FELIX, the free electron laser for infrared experiments. The system consists of a thermionic gun, a prebuncher,

Near-infrared laser-triggered carbon nanohorns for selective elimination of microbes

International Nuclear Information System (INIS)

Miyako, Eijiro; Nagata, Hideya; Hirano, Ken; Makita, Yoji; Nakayama, Ken-ichi; Hirotsu, Takahiro

2007-01-01

Carbon nanomaterials, such as carbon nanohorns and carbon nanotubes, have attracted considerable attention for their biomedical applications. We report here the first application of carbon nanohorns (CNHs) as potent laser therapeutic agents for highly selective elimination of microorganisms. This is the first report, supported by direct observations, of the highly selective elimination of yeast and bacteria (Saccharomyces cerevisiae and Escherichia coli) by employing molecular recognition element-CNH complexes and a near-infrared laser

Nanoparticles and their tailoring with laser light

International Nuclear Information System (INIS)

Hubenthal, Frank

2009-01-01

Monodisperse noble metal nanoparticles are of tremendous interest for numerous applications, such as surface-enhanced Raman spectroscopy, catalysis or biosensing. However, preparation of monodisperse metal nanoparticles is still a challenging task, because typical preparation methods yield nanoparticle ensembles with broad shape and/or size distributions. To overcome this drawback, tailoring of metal nanoparticles with laser light has been developed, which is based on the pronounced shape- and size-dependent optical properties of metal nanoparticles. I will demonstrate that nanoparticle tailoring with ns-pulsed laser light is a suitable method to prepare nanoparticle ensembles with a narrow shape and/or size distribution. While irradiation with ns-pulsed laser light during nanoparticle growth permits a precise shape tailoring, post-grown irradiation allows a size tailoring. For example, the initial broad Gaussian size distribution of silver nanoparticles on quartz substrates with a standard deviation of σ= 30% is significantly reduced to as little as σ= 10% after tailoring. This paper addresses teachers of undergraduate and advanced school level as well as students. It assumes some fundamental knowledge in solid-state physics, thermodynamics and resonance vibration.

Near-infrared laser, time domain, breast tumour detection system

International Nuclear Information System (INIS)

Joblin, A.J.

1996-01-01

Full text: The use of near-infrared laser, time domain techniques have been proposed for some time now as an alternative to X-ray mammography, as a means of mass screening for breast disease. The great driving force behind this research has been that near-infrared photons are a non-ionising radiation, which affords a greater degree of patient safety than when using X-rays. This would mean that women at risk of breast disease could be screened with a near-infrared laser imaging system, much more regularly than with an X-ray mammography system, which should allow for the earlier detection and treatment of breast disease. This paper presents a theoretical investigation of the performance of a near-infrared, time domain breast imaging system. The performance of the imaging system is characterised by the resolution and contrast parameters, which were studied using a numerical finite difference calculation method. The finite difference method is used to solve the diffusion equation for the photon transport through the inhomogeneous breast tissue medium. Optimal performance was found to be obtained with short photon times of flight. However the signal to noise ratio decreases rapidly as the photon time of flight is decreased. The system performance will therefore be limited by the noise equivalent power of the time resolved detection system, which is the signal incident on the time resolved detection system which gives a signal to noise ratio of 1:1. Photon times of flight shorter than 500 ps are not practical with current technology, which places limits on the resolution and contrast. The photon signal throughput can be increased by increasing the size of the laser beam width, by increasing the size of the aperture stop of the detector, by increasing the laser pulse duration or decreasing the detector time resolution. Best system performance is found by optimising these parameters for a given time gating and detector system characteristic (NEP). It was found that the

Comparison of infrared laser beam shaping by diffractive and refractive methods

CSIR Research Space (South Africa)

Forbes, A

2005-08-01

Full Text Available Infra-red laser beam shaping has the inherent difficulty that simple ray tracing methods often yield anomalous results, due primarily to the propagation effects at longer wavelengths. Techniques based on diffraction theory have been developed...

Laser wakefield accelerator based light sources: potential applications and requirements

Energy Technology Data Exchange (ETDEWEB)

Albert, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). NIF and Photon Sciences; Thomas, A. G. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences; Mangles, S. P.D. [Imperial College, London (United Kingdom). Blackett Lab.; Banerjee, S. [Univ. of Nebraska, Lincoln, NE (United States); Corde, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Flacco, A. [ENSTA, CNRS, Ecole Polytechnique, Palaiseau (France); Litos, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Neely, D. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Viera, J. [Univ. of Lisbon (Portugal). GoLP-Inst. de Plasmas e Fusao Nuclear-Lab. Associado; Najmudin, Z. [Imperial College, London (United Kingdom). Blackett Lab.; Bingham, R. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Joshi, C. [Univ. of California, Los Angeles, CA (United States). Dept. of Electrical Engineering; Katsouleas, T. [Duke Univ., Durham, NC (United States). Platt School of Engineering

2015-01-15

In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.

Modes in light wave propagating in semiconductor laser

Science.gov (United States)

Manko, Margarita A.

1994-01-01

The study of semiconductor laser based on an analogy of the Schrodinger equation and an equation describing light wave propagation in nonhomogeneous medium is developed. The active region of semiconductor laser is considered as optical waveguide confining the electromagnetic field in the cross-section (x,y) and allowing waveguide propagation along the laser resonator (z). The mode structure is investigated taking into account the transversal and what is the important part of the suggested consideration longitudinal nonhomogeneity of the optical waveguide. It is shown that the Gaussian modes in the case correspond to spatial squeezing and correlation. Spatially squeezed two-mode structure of nonhomogeneous optical waveguide is given explicitly. Distribution of light among the laser discrete modes is presented. Properties of the spatially squeezed two-mode field are described. The analog of Franck-Condon principle for finding the maxima of the distribution function and the analog of Ramsauer effect for control of spatial distribution of laser emission are discussed.

Plasmas and intense laser light

International Nuclear Information System (INIS)

Kennedy, E.T.

1984-01-01

The present article begins with a description of the laser technology required to reach the high irradiances of interest and provides a brief outline of the more important diagnostic techniques used in investigating the plasmas. An introduction to plasma waves is given and the linear and nonlinear excitation of waves is discussed. The remainder of the article describes some of the experimental evidence supporting the interpretation of the plasma behaviour at high laser-light intensities in terms of the excitation of plasma waves and the subsequent heating of plasma by these waves. (author)

The use of lasers as sources for Raman spectrometry, resonance Raman spectrometry, and light scattering

International Nuclear Information System (INIS)

Capitini, R.; Ceccaldi, M.; Leicknam, J.P.; Plus, R.

1975-01-01

The activity of the laboratory is principally centred on the determination of molecular structures and the study of molecular interactions in solution by infrared and Raman spectrometry. With the development of work on relatively large molecules, particularly biological molecules, it became necessary to complete information on the molecular weight and on the intra and intermolecular geometry and interactions of these bodies. In order to obtain these informations Rayleigh scattering and resonance Raman spectrometry were used. The advantages of using vibrational spectrometry, particularly Raman, in conjunction with the diffusion of light for these structural and molecular interaction studies is emphasized. It is shown that these two techniques could not have developed as they have done in the last few years without the use of lasers as light source [fr

Recent progress in diode-pumped mid-infrared vibronic solid-state lasers

International Nuclear Information System (INIS)

Sorokina, I.T.; Sorokin, E.; Mirov, S.; Schaffers, K.

2002-01-01

Full text: The last few years were marked by the increased interest of researchers towards the new class of transition-metal doped zinc chalcogenides. In particular Cr:ZnSe attracts a lot of attention as broadly tunable continuous-wave (cw), mode-locked and diode-pumped lasers operating around 2.5 mm. This interest is explained by the absence of other comparable tunable room-temperature laser sources in this spectral region. However, another member of the II-VI compounds family Cr:ZnS, has yet remained barely studied as a laser medium. Recently we demonstrated the first continuous-wave room-temperature tunable over more than 280 nm around 2.3 μm Cr 2+ :ZnS laser, pumped with a Co:MgF2 laser and yielding over 100 mW of output power. The most recent result is the development of a compact tunable over 700 nm continuous-wave room-temperature Cr 2+ :ZnS laser, pumped by the diode-pumped Er-fiber laser at 1.6 μm and generating 0.7 W of the linearly polarized radiation. We also demonstrated direct diode-pumping at 1.6 μm of the Cr 2+ :ZnS. Although the Cr:ZnS exhibited lower (relatively to the Cr:ZnSe) efficiency and output power due to the higher passive losses of the available Cr:ZnS samples, the analysis of the spectroscopic and laser data indicates the high potential of Cr:ZnS for compact broadly tunable mid-infrared systems, as well as for high power applications. The physics of the novel diode-pumped laser systems is highly interesting. It comprises the features of the ion-doped dielectric crystalline lasers and semiconductors. For example, we observe in these media, for the first time to our knowledge, a new nonlinear phenomenon, which is analogous to the opto-optical switching process, where the laser output of the diode-pumped continuous-wave Cr:ZnSe and Cr:ZnS lasers around 2.5 μm is modulated by only a few milliwatt of the visible (470-500 nm) and near-infrared radiation (740-770 nm). We present a physical explanation of the observed effect. Refs. 4 (author)

CO2 laser-fabricated cladding light strippers for high-power fiber lasers and amplifiers.

Science.gov (United States)

Boyd, Keiron; Simakov, Nikita; Hemming, Alexander; Daniel, Jae; Swain, Robert; Mies, Eric; Rees, Simon; Andrew Clarkson, W; Haub, John

2016-04-10

We present and characterize a simple CO2 laser processing technique for the fabrication of compact all-glass optical fiber cladding light strippers. We investigate the cladding light loss as a function of radiation angle of incidence and demonstrate devices in a 400 μm diameter fiber with cladding losses of greater than 20 dB for a 7 cm device length. The core losses are also measured giving a loss of cladding light stripping of a 300 W laser diode with minimal heating of the fiber coating and packaging adhesives.

Modeling of photoluminescence in laser-based lighting systems

Science.gov (United States)

Chatzizyrli, Elisavet; Tinne, Nadine; Lachmayer, Roland; Neumann, Jörg; Kracht, Dietmar

2017-12-01

The development of laser-based lighting systems has been the latest step towards a revolution in illumination technology brought about by solid-state lighting. Laser-activated remote phosphor systems produce white light sources with significantly higher luminance than LEDs. The weak point of such systems is often considered to be the conversion element. The high-intensity exciting laser beam in combination with the limited thermal conductivity of ceramic phosphor materials leads to thermal quenching, the phenomenon in which the emission efficiency decreases as temperature rises. For this reason, the aim of the presented study is the modeling of remote phosphor systems in order to investigate their thermal limitations and to calculate the parameters for optimizing the efficiency of such systems. The common approach to simulate remote phosphor systems utilizes a combination of different tools such as ray tracing algorithms and wave optics tools for describing the incident and converted light, whereas the modeling of the conversion process itself, i.e. photoluminescence, in most cases is circumvented by using the absorption and emission spectra of the phosphor material. In this study, we describe the processes involved in luminescence quantum-mechanically using the single-configurational-coordinate diagram as well as the Franck-Condon principle and propose a simulation model that incorporates the temperature dependence of these processes. Following an increasing awareness of climate change and environmental issues, the development of ecologically friendly lighting systems featuring low power consumption and high luminous efficiency is imperative more than ever. The better understanding of laser-based lighting systems is an important step towards that aim as they may improve on LEDs in the near future.

Low intensity infrared laser affects expression of oxidative DNA repair genes in mitochondria and nucleus

International Nuclear Information System (INIS)

Fonseca, A S; Magalhães, L A G; Mencalha, A L; Geller, M; Paoli, F

2014-01-01

Practical properties and physical characteristics of low intensity lasers have made possible their application to treat soft tissue diseases. Excitation of intracellular chromophores by red and infrared radiation at low energy fluences with increase of mitochondrial metabolism is the basis of the biostimulation effect but free radicals can be produced. DNA lesions induced by free radicals are repaired by the base excision repair pathway. In this work, we evaluate the expression of POLγ and APEX2 genes related to repair of mitochondrial and nuclear DNA, respectively. Skin and muscle tissue of Wistar rats were exposed to low intensity infrared laser at different fluences. One hour and 24 hours after laser exposure, tissue samples were withdrawn for total RNA extraction, cDNA synthesis, and evaluation of POLγ and APEX2 mRNA expression by real time quantitative polymerase chain reaction. Skin and muscle tissue of Wistar rats exposed to laser radiation show different expression of POLγ and APEX2 mRNA depending of the fluence and time after exposure. Our study suggests that a low intensity infrared laser affects expression of genes involved in repair of oxidative lesions in mitochondrial and nuclear DNA. (paper)

Treatment of the calcaneal spur with infrared laser

International Nuclear Information System (INIS)

Orellana, Alina; Larrea, Pedro; Hernandez, Adel; Combarro, Andres; Corcho, Carlos; Fernandez, Sandra; Morales, Omar; Porrua, Agustin; Perez Ares, Jose

2009-01-01

The treatment with low power laser offers a beneficial and regenerating effect over nervous, muscular and skeletal tissues, soft tissues, and skin. This therapy has been used for more than three decades, based on the properties and effects of lasers in almost all medical specialties, due to it constitutes a novel, painless, non invasive, and easy to apply, in addition to the absence of any risk for patient and to have very good clinical results. Knowing the biological effects of the low power laser therapy (analgesic, anti-inflammatory, an tissue regenerator), we were dedicated to investigate the analgesic effect achieved with the application of infrared laser radiation in patients that suffering form calcaneal spur, who attended to the Natural and Traditional Medical Service of the clinic '30 de november', from January 2005 to January 2008. The whole of patients was 62, and the sample included 52 individuals from different sexes, races, and ages between 20 and 80 years, excluding pregnant women and neoplasia patients. Pain relief was achieved since second session of treatment, with 61,5 % of cases cured and 38,5 % improved, no one was worse, neither keep the same initial symptoms. (Author)

The role of lasers and intense pulsed light technology in dermatology

Directory of Open Access Journals (Sweden)

Husain Z

2016-02-01

Full Text Available Zain Husain,1 Tina S Alster1,2 1Department of Dermatology, Georgetown University Hospital, 2Washington Institute of Dermatologic Laser Surgery, Washington, DC, USA Abstract: The role of light-based technologies in dermatology has expanded dramatically in recent years. Lasers and intense pulsed light have been used to safely and effectively treat a diverse array of cutaneous conditions, including vascular and pigmented lesions, tattoos, scars, and undesired hair, while also providing extensive therapeutic options for cosmetic rejuvenation and other dermatologic conditions. Dermatologic laser procedures are becoming increasingly popular worldwide, and demand for them has fueled new innovations and clinical applications. These systems continue to evolve and provide enhanced therapeutic outcomes with improved safety profiles. This review highlights the important roles and varied clinical applications that lasers and intense pulsed light play in the dermatologic practice. Keywords: laser, intense pulsed light, treatment, dermatology, technology

Mid-infrared pulsed laser ablation of the arterial wall. Mechanical origin of "acoustic" wall damage and its effect on wall healing

NARCIS (Netherlands)

van Erven, L.; van Leeuwen, T. G.; Post, M. J.; van der Veen, M. J.; Velema, E.; Borst, C.

1992-01-01

Pulsed mid-infrared lasers are an alternative to excimer lasers for transluminal angioplasty. The mid-infrared lasers, however, were reported to produce "acoustic" wall damage that might impair the immediate and long-term results. To study the immediate and long-term effects on the arterial wall,

Rapid prototyping of reflectors for vehicle lighting using laser activated remote phosphor

Science.gov (United States)

Lachmayer, Roland; Kloppenburg, Gerolf; Wolf, Alexander

2015-03-01

Bright white light sources are of significant importance for automotive front lighting systems. Today's upper class vehicles mainly use HID or LED as light source. As a further step in this development laser diode based systems offer high luminance, efficiency and allow the realization of new styling concepts and new dynamic lighting functions. These white laser diode systems can either be realized by mixing different spectral sources or by combining diodes with specific phosphors. Based on the approach of generating light using a laser and remote phosphor, lighting modules are manufactured. Four blue laser diodes (450 nm) are used to activate a phosphor coating and thus to achieve white light. A segmented paraboloid reflector generates the desired light distribution for an additional car headlamp. We use high speed milling and selective laser melting to build the reflector system for this lighting module. We compare the spectral reflection grade of these materials. Furthermore the generated modules are analyzed regarding their efficiency and light distribution. The use of Rapid Prototyping technologies allows an early validation of the chosen concept and is supposed to reduce cost and time in the product development process significantly. Therefor we discuss costs and times of the applied manufacturing technologies.

Infrared light extinction by charged dielectric core-coat particles

OpenAIRE

Thiessen, Elena; Heinisch, Rafael L.; Bronold, Franz X.; Fehske, Holger

2014-01-01

We study the effect of surplus electrons on the infrared extinction of dielectric particles with a core-coat structure and propose to use it for an optical measurement of the particle charge in a dusty plasma. The particles consist of an inner core with negative and an outer coat with positive electron affinity. Both the core and the coat give rise to strong transverse optical phonon resonances, leading to anomalous light scattering in the infrared. Due to the radial profile of the electron a...

Femtosecond few-cycle mid-infrared laser pulses

DEFF Research Database (Denmark)

Liu, Xing

The few-cycle pulses of mid-infrared (mid-IR, wavelength 2-10 microns) have attracted increasing attention owing to their great potentials for high order harmonic generation, time-resolved spectroscopy, precision of cutting and biomedical science.In this thesis, mid-IR frequency conversion.......2 - 5.5 μm with only one fixed pump wavelength, a feature absent in Kerr media. Finally, we experimentally observe supercontinuum generation spanning 1.5 octaves, generated in a 10 mm long silicon-rich nitride waveguide pumped by 100 pJ femtosecond pulses from an erbium fiber laser. The waveguide has...

Infrared tomography for diagnostic imaging of port wine stain blood vessels

Energy Technology Data Exchange (ETDEWEB)

Goodman, D. [Lawrence Livermore National Lab., CA (United States)

1994-11-15

The objective of this work is the development of Infrared Tomography (IRT) for detecting and characterizing subsurface chromophores in human skin. Characterization of cutaneous chromophores is crucial for advances in the laser treatment of pigmented lesions (e.g., port wine stain birthmarks and tatoos). Infrared tomography (IRT) uses a fast infrared focal plane array (IR-FPA) to detect temperature rises in a substrate induced by pulsed radiation. A pulsed laser is used to produce transient heating of an object. The temperature rise, due to the optical absorption of the pulsed laser light, creates an increase in infrared emission which is measured by the IR-FPA. Although the application of IRT to image subsurface cracks due to metal fatigue is a topic of great interest in the aircraft industry, the application to image subsurface chromophores in biological materials is novel. We present an image recovery method based on a constrained conjugate gradient algorithm that has obtained the first ever high quality images of port wine blood vessels.

SPECT Perfusion Imaging Demonstrates Improvement of Traumatic Brain Injury With Transcranial Near-infrared Laser Phototherapy.

Science.gov (United States)

Henderson, Theodore A; Morries, Larry D

2015-01-01

Traumatic brain injury (TBI) is a growing health concern affecting civilians and military personnel. Near-infrared (NIR) light has shown benefits in animal models and human trials for stroke and in animal models for TBI. Diodes emitting low-level NIR often have lacked therapeutic efficacy, perhaps failing to deliver sufficient radiant energy to the necessary depth. In this case report, a patient with moderate TBI documented in anatomical magnetic resonance imaging (MRI) and perfusion single-photon emission computed tomography (SPECT) received 20 NIR treatments in the course of 2 mo using a high-power NIR laser. Symptoms were monitored by clinical examination and a novel patient diary system specifically designed for this patient population. Clinical application of these levels of infrared energy for this patient with TBI yielded highly favorable outcomes with decreased depression, anxiety, headache, and insomnia, whereas cognition and quality of life improved. Neurological function appeared to improve based on changes in the SPECT by quantitative analysis. NIR in the power range of 10-15 W at 810 and 980 nm can safely and effectively treat chronic symptoms of TBI.

Ponderomotive and thermal filamentation of laser light

International Nuclear Information System (INIS)

Kruer, W.L.

1985-01-01

As targets are irradiated with longer, more energetic pulses of laser light, longer-scalelength plasmas are produced. Filamentation is a potentially important process in such plasmas. In this instability, perturbations in the intensity profile of an incident light beam grow in amplitude, causing the beam to break up into intense filaments. The instability arises when a local increase in the light intensity creates a depression in plasma density either directly, via the ponderomotive force, or indirectly, via enhanced collisional absorption and subsequent plasma expansion. The density depression refracts the light into the lower-density region, enhancing the intensity perturbations. The instability is termed either ponderomotive or thermal filamentation, depending on which mechanism generates the density depression. The analogous process involving the entire beam is called self-focusing. Filamentation can significantly affect laser-plasma coupling. Intensity enhancements can introduce or modify other instabilities, change the location of the energy deposition, and possibly aggravate deleterious collective effects such as hot-electron generation

Cosmic Infrared Background Fluctuations and Zodiacal Light

Science.gov (United States)

Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

2016-06-01

We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field at low ecliptic latitude where the zodiacal light intensity varies by factors of ˜2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (≳100″) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

Photothermal Therapy Using Gold Nanorods and Near-Infrared Light in a Murine Melanoma Model Increases Survival and Decreases Tumor Volume

Directory of Open Access Journals (Sweden)

Mary K. Popp

2014-01-01

Full Text Available Photothermal therapy (PTT treatments have shown strong potential in treating tumors through their ability to target destructive heat preferentially to tumor regions. In this paper we demonstrate that PTT in a murine melanoma model using gold nanorods (GNRs and near-infrared (NIR light decreases tumor volume and increases animal survival to an extent that is comparable to the current generation of melanoma drugs. GNRs, in particular, have shown a strong ability to reach ablative temperatures quickly in tumors when exposed to NIR light. The current research tests the efficacy of GNRs PTT in a difficult and fast growing murine melanoma model using a NIR light-emitting diode (LED light source. LED light sources in the NIR spectrum could provide a safer and more practical approach to photothermal therapy than lasers. We also show that the LED light source can effectively and quickly heat in vitro and in vivo models to ablative temperatures when combined with GNRs. We anticipate that this approach could have significant implications for human cancer therapy.

Dual-channel operation in a synchronously pumped optical parametric oscillator for the generation of broadband mid-infrared coherent light sources.

Science.gov (United States)

Liu, Pei; Wang, Sicong; He, Puyuan; Zhang, Zhaowei

2018-05-01

We report, to the best of our knowledge, a novel approach for generating broadband mid-infrared (mid-IR) light by implementing a dual-channel scheme in a synchronously pumped optical parametric oscillator (SPOPO). Two-channel operation was achieved by inserting a prism pair and two reflection mirrors inside an optical parametric oscillator (OPO) cavity. Pumped by a Yb-fiber laser, the OPO generated an idler wave at ∼3150  nm with a -10  dB bandwidth of ∼13.2  THz, which was twice as much as that of the pump source. This scheme represents a promising technical route to transform conventional SPOPOs into a device capable of generating mid-IR light with very broad instantaneous bandwidth.

Supercontinuum - broad as a lamp, bright as a laser, now in the mid-infrared

DEFF Research Database (Denmark)

Moselund, Peter M.; Petersen, Christian; Dupont, Sune

2012-01-01

Based on the experience gained developing our market leading visible spectrum supercontinuum sources NKT Photonics has built the first mid-infrared supercontinuum source based on modelocked picosecond fiber lasers. The source is pumped by a ≈ 2 um laser based on a combination of erbium and thuliu...

The osmotic fragility of human erythrocytes is inhibited by laser irradiation

International Nuclear Information System (INIS)

Habodaszova, D.; Sikurova, L.; Waczulikova, I.

2004-01-01

In this study we investigated the influence of green laser irradiation (532 nm, 30 mW, 31,7 J/cm 2 ) on the membrane integrity of human erythrocytes and compared the results with the effect of infrared laser irradiation (810 nm, 50 mW, 31,3 J/cm 2 ). To evaluate the membrane integrity of erythrocytes, one clinical parameter, the osmotic fragility, was investigated. We observed a decrease in osmotic fragility of the erythrocytes after irradiation by the green laser light as well as by the infrared laser compared to non-irradiated controls (Authors)

Vapor-phase infrared laser spectroscopy: from gas sensing to forensic urinalysis.

Science.gov (United States)

Bartlome, Richard; Rey, Julien M; Sigrist, Markus W

2008-07-15

Numerous gas-sensing devices are based on infrared laser spectroscopy. In this paper, the technique is further developed and, for the first time, applied to forensic urinalysis. For this purpose, a difference frequency generation laser was coupled to an in-house-built, high-temperature multipass cell (HTMC). The continuous tuning range of the laser was extended to 329 cm(-1) in the fingerprint C-H stretching region between 3 and 4 microm. The HTMC is a long-path absorption cell designed to withstand organic samples in the vapor phase (Bartlome, R.; Baer, M.; Sigrist, M. W. Rev. Sci. Instrum. 2007, 78, 013110). Quantitative measurements were taken on pure ephedrine and pseudoephedrine vapors. Despite featuring similarities, the vapor-phase infrared spectra of these diastereoisomers are clearly distinguishable with respect to a vibrational band centered at 2970.5 and 2980.1 cm(-1), respectively. Ephedrine-positive and pseudoephedrine-positive urine samples were prepared by means of liquid-liquid extraction and directly evaporated in the HTMC without any preliminary chromatographic separation. When 10 or 20 mL of ephedrine-positive human urine is prepared, the detection limit of ephedrine, prohibited in sports as of 10 microg/mL, is 50 or 25 microg/mL, respectively. The laser spectrometer has room for much improvement; its potential is discussed with respect to doping agents detection.

Observation of a rainbow of visible colors in a near infrared cascaded Raman fiber laser and its novel application as a diagnostic tool for length resolved spectral analysis

Science.gov (United States)

Aparanji, Santosh; Balaswamy, V.; Arun, S.; Supradeepa, V. R.

2018-02-01

In this work, we report and analyse the surprising observation of a rainbow of visible colors, spanning 390nm to 620nm, in silica-based, Near Infrared, continuous-wave, cascaded Raman fiber lasers. The cascaded Raman laser is pumped at 1117nm at around 200W and at full power we obtain 100 W at 1480nm. With increasing pump power at 1117nm, the fiber constituting the Raman laser glows in various hues along its length. From spectroscopic analysis of the emitted visible light, it was identified to be harmonic and sum-frequency components of various locally propagating wavelength components. In addition to third harmonic components, surprisingly, even 2nd harmonic components were observed. Despite being a continuous-wave laser, we expect the phase-matching occurring between the core-propagating NIR light with the cladding-propagating visible wavelengths and the intensity fluctuations characteristic of Raman lasers to have played a major role in generation of visible light. In addition, this surprising generation of visible light provides us a powerful non-contact method to deduce the spectrum of light propagating in the fiber. Using static images of the fiber captured by a standard visible camera such as a DSLR, we demonstrate novel, image-processing based techniques to deduce the wavelength component propagating in the fiber at any given spatial location. This provides a powerful diagnostic tool for both length and power resolved spectral analysis in Raman fiber lasers. This helps accurate prediction of the optimal length of fiber required for complete and efficient conversion to a given Stokes wavelength.

Near-Infrared Free-Radical and Free-Radical-Promoted Cationic Photopolymerizations by In-Source Lighting Using Upconverting Glass.

Science.gov (United States)

Kocaarslan, Azra; Tabanli, Sevcan; Eryurek, Gonul; Yagci, Yusuf

2017-11-13

A method is presented for the initiation of free-radical and free-radical-promoted cationic photopolymerizations by in-source lighting in the near-infrared (NIR) region using upconverting glass (UCG). This approach utilizes laser irradiation of UCG at 975 nm in the presence of fluorescein (FL) and pentamethyldiethylene triamine (PMDETA). FL excited by light emitted from the UCG undergoes electron-transfer reactions with PMDETA to form free radicals capable of initiating polymerization of methyl methacrylate. To execute the corresponding free-radical-promoted cationic polymerization of cyclohexene oxide, isobutyl vinyl ether, and N-vinyl carbazole, it was necessary to use FL, dimethyl aniline (DMA), and diphenyliodonium hexafluorophosphate as sensitizer, coinitiator, and oxidant, respectively. Iodonium ions promptly oxidize DMA radicals formed to the corresponding cations. Thus, cationic polymerization with efficiency comparable to the conventional irradiation source was achieved. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Infrared and laser-Raman spectroscopic studies of thermally-induced globular protein gels.

Science.gov (United States)

Clark, A H; Saunderson, D H; Suggett, A

1981-03-01

Infrared and laser-Raman spectroscopy have been used to follow secondary structure changes during the heat-set gelation of a number of aqueous (D2O) globular protein solutions. Measurements of the infrared Amide I' absorption band around 1650 cm-1, for BSA gels of varying clarity and texture, have shown that the very considerable variations in network structure underlying these materials are not reflected in obvious differences in secondary structure. In all cases aggregation is accompanied by development of beta-sheet of a kind common in fibrous protein systems, but for BSA at least this does not appear to vary significantly in amount from one gel type to another. Infrared studies of gels formed from other protein systems have confirmed this tendency for beta-sheet to develop during aggregation, and the tendency is further substantiated by laser-Raman evidence which provides the extra information that in most of the examples studied alpha-helix content simultaneously falls. From these, and other observations, some generalisations are made about the thermally-induced sol-to-gel transformations of globular proteins.

Hierarchical Models for Type Ia Supernova Light Curves in the Optical and Near Infrared

Science.gov (United States)

Mandel, Kaisey; Narayan, G.; Kirshner, R. P.

2011-01-01

I have constructed a comprehensive statistical model for Type Ia supernova optical and near infrared light curves. Since the near infrared light curves are excellent standard candles and are less sensitive to dust extinction and reddening, the combination of near infrared and optical data better constrains the host galaxy extinction and improves the precision of distance predictions to SN Ia. A hierarchical probabilistic model coherently accounts for multiple random and uncertain effects, including photometric error, intrinsic supernova light curve variations and correlations across phase and wavelength, dust extinction and reddening, peculiar velocity dispersion and distances. An improved BayeSN MCMC code is implemented for computing probabilistic inferences for individual supernovae and the SN Ia and host galaxy dust populations. I use this hierarchical model to analyze nearby Type Ia supernovae with optical and near infared data from the PAIRITEL, CfA3, and CSP samples and the literature. Using cross-validation to test the robustness of the model predictions, I find that the rms Hubble diagram scatter of predicted distance moduli is 0.11 mag for SN with optical and near infrared data versus 0.15 mag for SN with only optical data. Accounting for the dispersion expected from random peculiar velocities, the rms intrinsic prediction error is 0.08-0.10 mag for SN with both optical and near infrared light curves. I discuss results for the inferred intrinsic correlation structures of the optical-NIR SN Ia light curves and the host galaxy dust distribution captured by the hierarchical model. The continued observation and analysis of Type Ia SN in the optical and near infrared is important for improving their utility as precise and accurate cosmological distance indicators.

Characterization of silicon micro-strip sensors with a pulsed infra-red laser system for the CBM experiment at FAIR

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Pradeep [Goethe University, Frankfurt am Main (Germany); GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt (Germany); Eschke, Juergen [GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt (Germany); Facility for Anti-proton and Ion Research, GmbH, Darmstadt (Germany); Collaboration: CBM-Collaboration

2015-07-01

The Silicon Tracking System (STS) of the CBM experiment at FAIR is composed of 8 tracking stations comprising of 1292 double-sided silicon micro-strip sensors. A Laser Test System (LTS) has been developed for the quality assurance of prototype sensors. The aim is to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. Several prototype sensors with strip pitch of 50 and 58 μm have been tested, as well as a prototype module with realistic mechanical arrangement of sensor and read-out cables. The LTS is designed to measure sensor response in an automatized procedure across the sensor with focused laser beam (spot-size ∼ 12 μm, wavelength = 1060 nm). The pulse with duration (∼ 10 ns) and power (∼ 5 mW) of the laser pulses is selected such, that the absorption of the laser light in the 300 μm thick silicon sensors produces a number of about 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. Results from laser scans of prototype sensors and detector module are reported.

Next-generation mid-infrared sources

Science.gov (United States)

Jung, D.; Bank, S.; Lee, M. L.; Wasserman, D.

2017-12-01

The mid-infrared (mid-IR) is a wavelength range with a variety of technologically vital applications in molecular sensing, security and defense, energy conservation, and potentially in free-space communication. The recent development and rapid commercialization of new coherent mid-infrared sources have spurred significant interest in the development of mid-infrared optical systems for the above applications. However, optical systems designers still do not have the extensive optical infrastructure available to them that exists at shorter wavelengths (for instance, in the visible and near-IR/telecom wavelengths). Even in the field of optoelectronic sources, which has largely driven the growing interest in the mid-infrared, the inherent limitations of state-of-the-art sources and the gaps in spectral coverage offer opportunities for the development of new classes of lasers, light emitting diodes and emitters for a range of potential applications. In this topical review, we will first present an overview of the current state-of-the-art mid-IR sources, in particular thermal emitters, which have long been utilized, and the relatively new quantum- and interband-cascade lasers, as well as the applications served by these sources. Subsequently, we will discuss potential mid-infrared applications and wavelength ranges which are poorly served by the current stable of mid-IR sources, with an emphasis on understanding the fundamental limitations of the current source technology. The bulk of the manuscript will then explore both past and recent developments in mid-infrared source technology, including narrow bandgap quantum well lasers, type-I and type-II quantum dot materials, type-II superlattices, highly mismatched alloys, lead-salts and transition-metal-doped II-VI materials. We will discuss both the advantages and limitations of each of the above material systems, as well as the potential new applications which they might serve. All in all, this topical review does not aim

High Resolution Near Infrared Spectrometer to Study the Zodiacal Light Spectrum

Science.gov (United States)

Kutyrev, Alexander; Arendt, R.; Dwek, E.; Moseley, S. H.; Silverberg, R.; Rapchun, D.

2007-12-01

We are developing a near infrared spectrometer for measuring solar absorption lines in the zodiacal light in the near infrared region. R. Reynolds at el. (2004, ApJ 612, 1206) demonstrated that observing single Fraunhofer line can be a powerful tool for extracting zodiacal light parameters based on their measurements of the profile of the Mg I line at 5184 A. We are extending this technique to the near infrared with the primary goal of measuring the absolute intensity of the zodiacal light. This measurement will provide the crucial information needed to accurately subtract zodiacal emission from the DIRBE measurements to get a much higher quality measurement of the extragalactic IR background. The instrument design is based on a dual Fabry-Perot interferometer with a narrow band filter. Its double etalon design allows to achieve high spectral contrast to reject the bright out of band telluric OH emission. High spectral contrast is absolutely necessary to achieve detection limits needed to accurately measure the intensity of the absorption line. We present the design, estimated performance of the instrument with the expected results of the observing program. The project is supported by NASA ROSES-APRA grant.

Near-infrared light absorption by brown carbon in the ambient atmosphere

Science.gov (United States)

Chung, C.; Hoffer, A.; Beres, N. D.; Moosmüller, H.; Liu, C.; Green, M.; Kim, S. W.; Engelbrecht, J. P.; Gelencser, A.

2017-12-01

Organic aerosols have been assumed to have little-to-no absorption in the red and near-infrared spectral regions of solar radiation, even though a class of organic aerosols were shown to absorb significantly in these spectral regions. Here, we show that ambient atmospheric data from commonly-used 7-wavelength aethalometers contain evidence of abundant near-infrared light absorption by organic aerosol. This evidence comes from the absorption Ångström exponent over 880 950 nm, which often exceeds values explainable by fresh or coated black carbon, or mineral dust. This evidence is not due to an artifact from the instrument random errors or biases, either. The best explanation for these large 880/950 nm absorption Ångström exponent values in the aethalometer data is near-infrared light absorption by tar balls. Tar balls are among common particles from forest fire.

Augmented reality in laser laboratories

Science.gov (United States)

Quercioli, Franco

2018-05-01

Laser safety glasses block visibility of the laser light. This is a big nuisance when a clear view of the beam path is required. A headset made up of a smartphone and a viewer can overcome this problem. The user looks at the image of the real world on the cellphone display, captured by its rear camera. An unimpeded and safe sight of the laser beam is then achieved. If the infrared blocking filter of the smartphone camera is removed, the spectral sensitivity of the CMOS image sensor extends in the near infrared region up to 1100 nm. This substantial improvement widens the usability of the device to many laser systems for industrial and medical applications, which are located in this spectral region. The paper describes this modification of a phone camera to extend its sensitivity beyond the visible and make a true augmented reality laser viewer.

Multicenter clinical perspectives on a broadband infrared light device for skin tightening.

Science.gov (United States)

Taub, Amy Forman; Battle, Eliot F; Nikolaidis, Gregory

2006-09-01

Modalities for skin tightening include radiofrequency (RF) energy, lasers, and combination RF and diode lasers. A new broadband infrared light device (BILD) (Titan, Cutera, Inc, Brisbane, CA) targets water to achieve dermal heating and collagen remodeling for skin tightening. Although thousands of procedures have been performed worldwide with this device, only one article (to the author's knowledge) describing its performance in skin tightening has been published. Three US dermatologists report their experience with and provide their perspective on facial skin tightening with the BILD system. As early adopters, they each have 12 to 18 months experience with this system. One author (A.F.T.) treated 42 patients twice at 1-month intervals over 18 months. The mean improvement score was 1.83 (scale 0 to 4, with 4 denoting maximum improvement) with an average follow-up time of 3.7 months. More than 90% of treated patients showed visible improvement. No complications were observed and patient satisfaction was high. This paper presents the general consensus of the authors on patient selection and treatment protocol, their modifications of the manufacturer's treatment protocol, and the outcomes of 42 patients treated by one author (A.F.T.). The observations were gathered separately and turned out to be very similar. The recommendations are presented to help practitioners achieve consistently good results and avoid complications with the BILD procedure.

Eye safe laser range finders

International Nuclear Information System (INIS)

Snir, M.; Margaliot, M.; Amitzi, A.

2004-01-01

During the 1970's, Ruby (Q switched) laser based range finders with a wavelength of 694nm were first used. These lasers operated in a pulse mode within the visible light range and produced a risk for the eye retina. The laser beam striking the macula could damage the eye and might cause blindness. Over the years, Nd:YAG (Q switched) lasers were developed (operating at 1064nm) for range finding and designation uses. The wavelength of these lasers, operating in the near Infra-Red range (invisible), is also focused tightly on the retina. The human eye does not respond to the invisible light so there is no natural protection (eye blink reflex) as in the visible light. The operation of these lasers worldwide, especially when the laser beam is exposed, causes occasional eye accidents. Another risk is stemming from the use of observation systems with a high optical gain, in the laser operation areas, which enlarge the range of risk quite significantly. Therefore, research and development efforts were invested in order to introduce eye safe lasers. One of the solutions for this problem is presented in following document

Infrared and ultraviolet laser removal of crustose lichens on dolomite heritage stone

Energy Technology Data Exchange (ETDEWEB)

Sanz, Mikel; Oujja, Mohamed [Instituto de Química Física Rocasolano (IQFR), CSIC, Serrano 119, 28006 Madrid (Spain); Ascaso, Carmen; Ríos, Asunción de los; Pérez-Ortega, Sergio [Museo Nacional de Ciencia Naturales (MNCN), CSIC, Serrano 115 bis, 28006 Madrid (Spain); Souza-Egipsy, Virginia [Instituto de Ciencias Agrarias (ICA), CSIC, Serrano 115 bis, 28006 Madrid (Spain); Wierzchos, Jacek; Speranza, Mariela [Museo Nacional de Ciencia Naturales (MNCN), CSIC, Serrano 115 bis, 28006 Madrid (Spain); Cañamares, Maria Vega [Instituto de Estructura de la Materia (ICEM), CSIC, Serrano 121, 28006 Madrid (Spain); Castillejo, Marta, E-mail: marta.castillejo@iqfr.csic.es [Instituto de Química Física Rocasolano (IQFR), CSIC, Serrano 119, 28006 Madrid (Spain)

2015-08-15

Graphical abstract: - Highlights: • Laser irradiation at 1064 nm (IR) or 355 nm (UV) partially removes epilithic lichens on dolostone. • Irradiation in a sequential, dual IR–UV mode efficiently eliminates lichen thalli. • Dual IR–UV irradiation mode induces severe damage on endolithic colonizers of dolostone. - Abstract: Laser removal of biodeteriogen layers warrants detailed studies due to the advantages it brings with respect to mechanical elimination or the use of biocides. We have investigated elimination of biological crusts on dolomite stones from heritage sites in central Spain. The samples were colonized by epilithic crustose lichens of different species, such as Caloplaca sp. and Verrucaria nigrescens. A comparative study was carried out by applying infrared (1064 nm) and ultraviolet (355 nm) nanosecond laser pulses and sequences pulses of the two wavelengths using a Q-switched Nd:YAG system. To detect anatomical and ultrastructural damage to the lichens, and to assess possible morphological and chemical changes on the underlying stone induced by laser irradiation, we used stereomicroscopy, scanning electron microscopy with backscattered electron imaging and Fourier transform Raman spectroscopy. The optimal conditions for removal of the colonization crust, while ensuring preservation of the lithic substrate, were obtained for dual infrared-ultraviolet sequential irradiation.

Infrared laser ablation atmospheric pressure photoionization mass spectrometry.

Science.gov (United States)

Vaikkinen, Anu; Shrestha, Bindesh; Kauppila, Tiina J; Vertes, Akos; Kostiainen, Risto

2012-02-07

In this paper we introduce laser ablation atmospheric pressure photoionization (LAAPPI), a novel atmospheric pressure ion source for mass spectrometry. In LAAPPI the analytes are ablated from water-rich solid samples or from aqueous solutions with an infrared (IR) laser running at 2.94 μm wavelength. Approximately 12 mm above the sample surface, the ablation plume is intercepted with an orthogonal hot solvent (e.g., toluene or anisole) jet, which is generated by a heated nebulizer microchip and directed toward the mass spectrometer inlet. The ablated analytes are desolvated and ionized in the gas-phase by atmospheric pressure photoionization using a 10 eV vacuum ultraviolet krypton discharge lamp. The effect of operational parameters and spray solvent on the performance of LAAPPI is studied. LAAPPI offers ~300 μm lateral resolution comparable to, e.g., matrix-assisted laser desorption ionization. In addition to polar compounds, LAAPPI efficiently ionizes neutral and nonpolar compounds. The bioanalytical application of the method is demonstrated by the direct LAAPPI analysis of rat brain tissue sections and sour orange (Citrus aurantium) leaves. © 2012 American Chemical Society

New enhanced sensitivity infrared laser spectroscopy techniques applied to reactive plasmas and trace gas detection

NARCIS (Netherlands)

Welzel, S.

2009-01-01

Infrared laser absorption spectroscopy (IRLAS) employing both tuneable diode and quantum cascade lasers (TDLs, QCLs) has been applied with both high sensitivity and high time resolution to plasma diagnostics and trace gas measurements. TDLAS combined with a conventional White type multiple pass cell

Design optimization of a compact photonic crystal microcavity based on slow light and dispersion engineering for the miniaturization of integrated mode-locked lasers

Science.gov (United States)

Kemiche, Malik; Lhuillier, Jérémy; Callard, Ségolène; Monat, Christelle

2018-01-01

We exploit slow light (high ng) modes in planar photonic crystals in order to design a compact cavity, which provides an attractive path towards the miniaturization of near-infrared integrated fast pulsed lasers. By applying dispersion engineering techniques, we can design structures with a low dispersion, as needed by mode-locking operation. Our basic InP SiO2 heterostructure is robust and well suited to integrated laser applications. We show that an optimized 30 μm long cavity design yields 9 frequency-equidistant modes with a FSR of 178 GHz within a 11.5 nm bandwidth, which could potentially sustain the generation of optical pulses shorter than 700 fs. In addition, the numerically calculated quality factors of these modes are all above 10,000, making them suitable for reaching laser operation. Thanks to the use of a high group index (28), this cavity design is almost one order of magnitude shorter than standard rib-waveguide based mode-locked lasers. The use of slow light modes in planar photonic crystal based cavities thus relaxes the usual constraints that tightly link the device size and the quality (peak power, repetition rate) of the pulsed laser signal.

Design optimization of a compact photonic crystal microcavity based on slow light and dispersion engineering for the miniaturization of integrated mode-locked lasers

Directory of Open Access Journals (Sweden)

Malik Kemiche

2018-01-01

Full Text Available We exploit slow light (high ng modes in planar photonic crystals in order to design a compact cavity, which provides an attractive path towards the miniaturization of near-infrared integrated fast pulsed lasers. By applying dispersion engineering techniques, we can design structures with a low dispersion, as needed by mode-locking operation. Our basic InP SiO2 heterostructure is robust and well suited to integrated laser applications. We show that an optimized 30 μm long cavity design yields 9 frequency-equidistant modes with a FSR of 178 GHz within a 11.5 nm bandwidth, which could potentially sustain the generation of optical pulses shorter than 700 fs. In addition, the numerically calculated quality factors of these modes are all above 10,000, making them suitable for reaching laser operation. Thanks to the use of a high group index (28, this cavity design is almost one order of magnitude shorter than standard rib-waveguide based mode-locked lasers. The use of slow light modes in planar photonic crystal based cavities thus relaxes the usual constraints that tightly link the device size and the quality (peak power, repetition rate of the pulsed laser signal.

Changes of retinal light sensitivity after YAG-laser capsulotomy

International Nuclear Information System (INIS)

Pahor, D.; Gracner, B.

2003-01-01

The aim of this prospective study was to investigate the changes of retinal light sensitivity of central visual field in patients with posterior capsule opacification (PCO) after YAG-laser capsulotomy. Our study includes 18 eyes ( 18 patients) with PCO after phacoemulsification and intraocular lens implantation. In all patients YAG-laser capsulotomy was performed. In all patients, a threshold visual field analysis was carried out with the C 30-2 program of the automated Humphrey Field Analyzer before and one month after the procedure. In all patients a significant improvement of visual acuity was observed one month after capsulotomy (p 0.00004). One month after YAG-laser treatment, a significant improvement of retinal light sensitivity in the central visual field was also observed. The average MD (mean deviation) before the procedure was -6.88 db (±3.9, max. -11.7, min. 2.17) and after the procedure --4.58 db (±4.37, max. -10.87, min. +0.51). The improvement in MD was statistically significant (p = 0.00475). No correlation was established between the improvement of retinal light sensitivity and patient age or the size of capsulotomy. Our study shows that the improvement of retinal light sensitivity is significant after YAG-laser capsulotomy and does not depend on patient age or capsulotomy size. (author)

The Investigation of Property of Radiation and Absorbed of Infrared Lights of the Biological Tissues

Science.gov (United States)

Pang, Xiao-Feng; Deng, Bo; Xiao, He-Lan; Cai, Guo-Ping

2010-04-01

The properties of absorption of infrared light for collagen, hemoglobin, bivine serum albumen (BSA) protein molecules with α- helix structure and water in the living systems as well as the infrared transmission spectra for person’s skins and finger hands of human body in the region of 400-4000 cm-1 (i.e., wavelengths of 2-20 μm) have been collected and determined by using a Nicolet Nexus 670 FT-IR Spectrometer, a Perkin Elmer GX FT-IR spectrometer, an OMA (optical multichannel analysis) and an infrared probe systems, respectively. The experimental results obtained show that the protein molecules and water can all absorb the infrared lights in the ranges of 600-1900 cm-1 and 2900-3900 cm-l, but their properties of absorption are somewhat different due to distinctions of their structure and conformation and molecular weight. We know from the transmission spectra of person’s finger hands and skin that the infrared lights with wavelengths of 2 μm-7 μm can not only transmit over the person’s skin and finger hands, but also be absorbed by the above proteins and water in the living systems. Thus, we can conclude from this study that the human beings and animals can absorb the infrared lights with wavelengths of 2 μm-7 μm.

Generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser in a cascade of nonlinear crystals

DEFF Research Database (Denmark)

Hansen, Anders Kragh; Jensen, Ole Bjarlin; Sumpf, Bernd

2014-01-01

Many applications, e.g., within biomedicine stand to benefit greatly from the development of diode laser-based multi- Watt efficient compact green laser sources. The low power of existing diode lasers in the green area (about 100 mW) means that the most promising approach remains nonlinear...... frequency conversion of infrared tapered diode lasers. Here, we describe the generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser, itself yielding 10 W at 1063 nm. This SHG is performed in single pass through a cascade of two PPMgO:LN crystals with re...... power of 3.5 W corresponds to a power enhancement greater than 2 compared to SHG in each of the crystals individually and is the highest visible output power generated by frequency conversion of a single diode laser. Such laser sources provide the necessary pump power for biophotonics applications...

Surface modification of UHMWPE with infrared femtosecond laser

Energy Technology Data Exchange (ETDEWEB)

Fernandez-Pradas, J.M., E-mail: jmfernandez@ub.edu [Departament de Fisica Aplicada i Optica, Universitat de Barcelona Marti i Franques 1, E-08028 Barcelona (Spain); Naranjo-Leon, S.; Morenza, J.L.; Serra, P. [Departament de Fisica Aplicada i Optica, Universitat de Barcelona Marti i Franques 1, E-08028 Barcelona (Spain)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Ultra High Molecular Weight Polyethylene surface was modified with femtosecond laser pulses at 1027 nm wavelength. Black-Right-Pointing-Pointer Surface roughness is increased. Black-Right-Pointing-Pointer Ablation efficiency is maximum for 6 {mu}J pulses. Black-Right-Pointing-Pointer Irradiated surfaces remain almost chemically unaltered. - Abstract: Ultra-high-molecular-weight polyethylene (UHMWPE) is a polymer with mechanical and corrosion properties, which make it appropriate for using in biomedical devices such as hip and knee prostheses. The surface morphology and chemistry of UHMWPE influence its biocompatibility. A laser with wavelength at 1027 nm delivering 450 fs pulses at a repetition rate of 1 kHz is used to modify the surface of UHMWPE samples with 0.45 {mu}m root mean square surface roughness. Micrometric resolution is achieved with the use of a focusing lens of 0.25 NA and pulse energies of few microjoules. The study focuses in the influence of different pulse energies and pulse overlaps on the laser-induced surface roughness and ablation yield. Confocal microscopy is used to characterize changes in the morphology of the irradiated surfaces, and their chemical structure is analyzed by attenuated total reflectance infrared and Raman spectroscopies. The roughness increases as the pulse energy increases until it reaches a maximum. The ablation yield increases with the pulse energy and pulse overlap. However, the ablation yield per pulse is lower for higher pulse overlap. Pulses of 6 {mu}J have the highest ablation efficiency. Infrared and Raman spectra of samples irradiated with low energy pulses are similar to those of the pristine sample. However, some C=C and C=O bonds can be detected after irradiation with the highest pulse energies.

Picosecond dissociation of amyloid fibrils with infrared laser: A nonequilibrium simulation study

Energy Technology Data Exchange (ETDEWEB)

Hoang Viet, Man; Roland, Christopher, E-mail: cmroland@ncsu.edu; Sagui, Celeste, E-mail: sagui@ncsu.edu [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States); Derreumaux, Philippe; Nguyen, Phuong H., E-mail: phuong.nguyen@ibpc.fr [Laboratoire de Biochimie Théorique, UPR 9080, CNRS Université Denis Diderot, Sorbonne Paris Cité IBPC, 13 rue Pierre et Marie Curie, 75005 Paris (France); Li, Mai Suan [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Institute for Computational Science and Technology, SBI Building, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City (Viet Nam)

2015-10-21

Recently, mid-infrared free-electron laser technology has been developed to dissociate amyloid fibrils. Here, we present a theoretical framework for this type of experiment based on laser-induced nonequilibrium all-atom molecular dynamics simulations. We show that the fibril is destroyed due to the strong resonance between its amide I vibrational modes and the laser field. The effects of laser irradiation are determined by a balance between fibril formation and dissociation. While the overall rearrangements of the fibril finish over short time scales, the interaction between the peptides and the solvent continues over much longer times indicating that the waters play an important role in the dissociation process. Our results thus provide new insights into amyloid fibril dissociation by laser techniques and open up new venues to investigate the complex phenomena associated with amyloidogenesis.

Near infrared photoluminescence properties of porous silicon prepared under the influence of light illumination

International Nuclear Information System (INIS)

Hamadeh, H; Naddaf, M; Jazmati, A

2008-01-01

Porous silicon (PS) has been prepared by anodic etching of boron doped silicon under the influence of monochromatic light illumination. The optical properties of the PS samples have been investigated using temperature dependent photoluminescence (PL) spectroscopy. An overall enhancement of the infrared luminescence yield is caused by the light illumination. In the visible spectral range, changes at the low energy side of the broad PL band were observed. In the near infrared spectral range, a new PL band at 850 nm, which is strongly correlated with light illumination, was detected. The new PL band disappears once blue light is used, whereas an increase in its intensity is observed, when the etching is performed under the illumination of light with wavelengths close to the band gap. By increasing the temperature, the 850 nm transition band grows at the expense of the main near infrared transition at 1100 nm. The recombination characteristics of this PL band are indicative of its extrinsic nature. The macroscopic morphology shows strong dependence on the wavelength of the illumination light. Photoassisted preparation could provide a tool for the control of the optical and structural properties of PS.

Near infrared photoluminescence properties of porous silicon prepared under the influence of light illumination

Energy Technology Data Exchange (ETDEWEB)

Hamadeh, H; Naddaf, M; Jazmati, A [Department of Physics, Atomic Energy Commission of Syria, PO Box 6091, Damascus (Syrian Arab Republic)], E-mail: Scientific8@aec.org.sy

2008-12-21

Porous silicon (PS) has been prepared by anodic etching of boron doped silicon under the influence of monochromatic light illumination. The optical properties of the PS samples have been investigated using temperature dependent photoluminescence (PL) spectroscopy. An overall enhancement of the infrared luminescence yield is caused by the light illumination. In the visible spectral range, changes at the low energy side of the broad PL band were observed. In the near infrared spectral range, a new PL band at 850 nm, which is strongly correlated with light illumination, was detected. The new PL band disappears once blue light is used, whereas an increase in its intensity is observed, when the etching is performed under the illumination of light with wavelengths close to the band gap. By increasing the temperature, the 850 nm transition band grows at the expense of the main near infrared transition at 1100 nm. The recombination characteristics of this PL band are indicative of its extrinsic nature. The macroscopic morphology shows strong dependence on the wavelength of the illumination light. Photoassisted preparation could provide a tool for the control of the optical and structural properties of PS.

Near infrared photoluminescence properties of porous silicon prepared under the influence of light illumination

International Nuclear Information System (INIS)

Hamadeh, H.; Naddaf, M.; Jazmati, A.

2009-01-01

Porous silicon (PS) has been prepared by anodic etching of boron doped silicon under the influence of monochromatic light illumination. The optical properties of the PS samples have been investigated using temperature dependent photoluminescence (PL) spectroscopy. An overall enhancement of the infrared luminescence yield is caused by the light illumination. In the visible spectral range, changes at the low energy side of the broad PL band were observed. In the near infrared spectral range, a new PL band at 850 nm, which is strongly correlated with light illumination, was detected. The new PL band disappears once blue light is used, whereas an increase of its intensity is observed, when the etching is performed under the illumination of light with wavelengths close to the band gap. By increasing the temperature, the 850 nm transition band grows at the expense of the main near infrared transition at 1100 nm. The recombination characteristics of this PL band are indicative of its extrinsic nature. The macroscopic morphology shows strong dependence on the wavelength of the illumination light. Photoassisted preparation could provide a tool for the control of the optical and structural properties of PS. (author)

Near infrared photoluminescence properties of porous silicon prepared under the influence of light illumination

Science.gov (United States)

Hamadeh, H.; Naddaf, M.; Jazmati, A.

2008-12-01

Porous silicon (PS) has been prepared by anodic etching of boron doped silicon under the influence of monochromatic light illumination. The optical properties of the PS samples have been investigated using temperature dependent photoluminescence (PL) spectroscopy. An overall enhancement of the infrared luminescence yield is caused by the light illumination. In the visible spectral range, changes at the low energy side of the broad PL band were observed. In the near infrared spectral range, a new PL band at 850 nm, which is strongly correlated with light illumination, was detected. The new PL band disappears once blue light is used, whereas an increase in its intensity is observed, when the etching is performed under the illumination of light with wavelengths close to the band gap. By increasing the temperature, the 850 nm transition band grows at the expense of the main near infrared transition at 1100 nm. The recombination characteristics of this PL band are indicative of its extrinsic nature. The macroscopic morphology shows strong dependence on the wavelength of the illumination light. Photoassisted preparation could provide a tool for the control of the optical and structural properties of PS.

Impact of mismatched and misaligned laser light sheet profiles on PIV performance

Science.gov (United States)

Grayson, K.; de Silva, C. M.; Hutchins, N.; Marusic, I.

2018-01-01

The effect of mismatched or misaligned laser light sheet profiles on the quality of particle image velocimetry (PIV) results is considered in this study. Light sheet profiles with differing widths, shapes, or alignment can reduce the correlation between PIV images and increase experimental errors. Systematic PIV simulations isolate these behaviours to assess the sensitivity and implications of light sheet mismatch on measurements. The simulations in this work use flow fields from a turbulent boundary layer; however, the behaviours and impacts of laser profile mismatch are highly relevant to any fluid flow or PIV application. Experimental measurements from a turbulent boundary layer facility are incorporated, as well as additional simulations matched to experimental image characteristics, to validate the synthetic image analysis. Experimental laser profiles are captured using a modular laser profiling camera, designed to quantify the distribution of laser light sheet intensities and inform any corrective adjustments to an experimental configuration. Results suggest that an offset of just 1.35 standard deviations in the Gaussian light sheet intensity distributions can cause a 40% reduction in the average correlation coefficient and a 45% increase in spurious vectors. Errors in measured flow statistics are also amplified when two successive laser profiles are no longer well matched in alignment or intensity distribution. Consequently, an awareness of how laser light sheet overlap influences PIV results can guide faster setup of an experiment, as well as achieve superior experimental measurements.

Multi-channel up-conversion infrared spectrometer and method of detecting a spectral distribution of light

DEFF Research Database (Denmark)

2015-01-01

A multi-channel infrared spectrometer for detecting an infrared spectrum of light received from an object. The spectrometer comprises a wavelength converter system comprising a nonlinear material and having an input side and an output side. The wavelength converter system comprises at least a first...... on the first side into light in a second output wavelength range output on the second side. The spectrometer further comprises a demultiplexer configured for demultiplexing light in the first up-conversion channel and light in the second up-conversion channel. The demultiplexer is located on the first side...

Perovskite Materials for Light-Emitting Diodes and Lasers.

Science.gov (United States)

Veldhuis, Sjoerd A; Boix, Pablo P; Yantara, Natalia; Li, Mingjie; Sum, Tze Chien; Mathews, Nripan; Mhaisalkar, Subodh G

2016-08-01

Organic-inorganic hybrid perovskites have cemented their position as an exceptional class of optoelectronic materials thanks to record photovoltaic efficiencies of 22.1%, as well as promising demonstrations of light-emitting diodes, lasers, and light-emitting transistors. Perovskite materials with photoluminescence quantum yields close to 100% and perovskite light-emitting diodes with external quantum efficiencies of 8% and current efficiencies of 43 cd A(-1) have been achieved. Although perovskite light-emitting devices are yet to become industrially relevant, in merely two years these devices have achieved the brightness and efficiencies that organic light-emitting diodes accomplished in two decades. Further advances will rely decisively on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional perovskites, nanostructures, charge-transport materials, and device processing with architectural innovations. Here, the rapid advancements in perovskite light-emitting devices and lasers are reviewed. The key challenges in materials development, device fabrication, operational stability are addressed, and an outlook is presented that will address market viability of perovskite light-emitting devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of SHG Power Modulation by Wavelength Detuning of DFB- and DBR-Tapered Laser Diodes

DEFF Research Database (Denmark)

Christensen, Mathias; Hansen, Anders Kragh; Noordegraaf, Danny

2016-01-01

of the response of the second harmonic light to perturbations of the infrared laser diode and compare how the response differs for DFB- and DBR-Tapered laser diodes. We show that the visible light can be modulated from CW to kHz with modulation depths above 90% by wavelength detuning the laser diode.......Pulsed visible lasers are used for a number of applications such as laser displays and medical treatments. Generating this visible light by direct frequency doubling of high power diode lasers opens new possibilities on how the power modulation can be performed. We present an investigation...

Effects of ultraviolet radiation, visible light, and infrared radiation on erythema and pigmentation: a review.

Science.gov (United States)

Sklar, Lindsay R; Almutawa, Fahad; Lim, Henry W; Hamzavi, Iltefat

2013-01-01

The effects of ultraviolet radiation, visible light, and infrared radiation on cutaneous erythema, immediate pigment darkening, persistent pigment darkening, and delayed tanning are affected by a variety of factors. Some of these factors include the depth of cutaneous penetration of the specific wavelength, the individual skin type, and the absorption spectra of the different chromophores in the skin. UVB is an effective spectrum to induce erythema, which is followed by delayed tanning. UVA induces immediate pigment darkening, persistent pigment darkening, and delayed tanning. At high doses, UVA (primarily UVA2) can also induce erythema in individuals with skin types I-II. Visible light has been shown to induce erythema and a tanning response in dark skin, but not in fair skinned individuals. Infrared radiation produces erythema, which is probably a thermal effect. In this article we reviewed the available literature on the effects of ultraviolet radiation, visible light, and infrared radiation on the skin in regards to erythema and pigmentation. Much remains to be learned on the cutaneous effects of visible light and infrared radiation.

Interstitial near-infrared photoimmunotherapy: effective treatment areas and light doses needed for use with fiber optic diffusers.

Science.gov (United States)

Okuyama, Shuhei; Nagaya, Tadanobu; Sato, Kazuhide; Ogata, Fusa; Maruoka, Yasuhiro; Choyke, Peter L; Kobayashi, Hisataka

2018-02-16

Near-infrared photoimmunotherapy (NIR-PIT), a promising cancer therapy utilizing an antibody-photoabsorber conjugate (APC) and NIR light, which induces rapid necrotic cell death only in APC-bound cells. Effective NIR-PIT in mouse models has been achieved using superficial light illumination (SLI) with light emitting diodes (LEDs) or lasers, but in the clinical setting, fiber optic diffusers have been employed to deliver light to deeper tumors. However, the performance of NIR light in tissue delivered by fiber optic diffusers is poorly understood. Here, we investigated NIR-PIT using a cylindrical fiber optic diffuser in a mouse model of A431 tumors. NIR-PIT with 100 J/cm, the same light dose used in clinical trials of NIR-PIT, was applied after insertion of the diffuser within the tumor bed, and then both bioluminescence and fluorescence imaging were analyzed to assess the therapeutic efficacy. The diffuser can deliver adequate NIR light dose for effective NIR-PIT to the A431 tumor at a distance of approximately 1 cm around the light source at 100 J/cm. At 50 J/cm NIR light effective NIR-PIT was reduced to a distance of 5 - 7 mm diameter around the light source. These results indicate that the energy of interstitial light (measured in Joules/cm) administered via a fiber diffuser determines the depth of effective NIR-PIT around the diffuser and determines the spacing at which such diffusers should be placed to entirely cover the tumor. Thermal measurements demonstrate that interstitial light for NIR-PIT does not cause damage to the skin overlying the diffuser.

Laser induced energy transfer

International Nuclear Information System (INIS)

Falcone, R.W.

1979-01-01

Two related methods of rapidly transferring stored energy from one excited chemical species to another are described. The first of these, called a laser induced collision, involves a reaction in which the energy balance is met by photons from an intense laser beam. A collision cross section of ca 10 - 17 cm 2 was induced in an experiment which demonstrated the predicted dependence of the cross section on wavelength and power density of the applied laser. A second type of laser induced energy transfer involves the inelastic scattering of laser radiation from energetically excited atoms, and subsequent absorption of the scattered light by a second species. The technique of producing the light, ''anti-Stokes Raman'' scattering of visible and infrared wavelength laser photons, is shown to be an efficient source of narrow bandwidth, high brightness, tunable radiation at vacuum ultraviolet wavelengths by using it to excite a rare gas transition at 583.7 A. In addition, this light source was used to make the first measurement of the isotopic shift of the helium metastable level at 601 A. Applications in laser controlled chemistry and spectroscopy, and proposals for new types of lasers using these two energy transfer methods are discussed

Temporally coherent x-ray laser with the high order harmonic light

International Nuclear Information System (INIS)

Hasegawa, Noboru; Kawachi, Tetsuya; Kishimoto, Maki; Sukegawa, Kouta; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Kawazome, Hayato; Nagashima, Keisuke

2005-01-01

We obtained the neon-like manganese x-ray laser with the injection of the high order harmonic light as the seed x-ray at the wavelength of 26.9 nm for the purpose of generation of the temporally coherent x-ray laser. The x-ray amplifier, which has quite narrow spectral width, selected and amplified the temporally coherent mode of the harmonic light. The temporal coherence of the mode selected harmonic light was nearly transform limited pulse, and the obtained x-ray laser with the seed x-ray expected to be nearly temporally coherent x-ray. (author)

White light emission from Er2O3 nano-powder excited by infrared radiation

Science.gov (United States)

Tabanli, Sevcan; Eryurek, Gonul; Di Bartolo, Baldassare

2017-07-01

Phosphors of Er2O3 nano-crystalline powders were synthesized by the thermal decomposition method. The structural properties of the nano-powders were investigated with XRD and HRTEM measurements. The cubic phase with a = 10.540 Å was the only phase observed. The average crystalline sizes and the widths of the grain size distribution curves were determined to be 27.2, 18.7 and 9.7 nm, respectively. The spectroscopic properties of the Er2O3 nano-powder were studied by measuring the luminescence, decay and rise patterns under 808 and 975 nm diode laser excitations. A peculiar effect of the pressure was observed since an optically active ion (Er) is part of the complex and not a dopant. A broad band of the white light emission combined with blue, green and red up-conversion emission bands of Er3+ ions were observed at 0.03 mbar pressure under both excitation wavelengths. Only, an intense broad band white light emission was observed from these nanocrystals at atmospheric pressure. Rising patterns show that the white light intensity reaches its maximum value more rapidly under 975 nm excitation although it decays slower than that of 808 nm excitation. The color quality parameters such as the color coordinate (CRI), correlated color temperature and the color rendering index were found to vary with both the excitation wavelength and the ambient pressure indicating that these nanocrystals could be considered good white light emitting source under the infrared excitations.

Novel mid-infrared imaging system based on single-mode quantum cascade laser illumination and upconversion

DEFF Research Database (Denmark)

Tomko, Jan; Junaid, Saher; Tidemand-Lichtenberg, Peter

2017-01-01

Compared to the visible or near-infrared (NIR) spectral regions, there is a lack of very high sensitivity detectors in the mid-infrared (MIR) that operate near room temperature. Upconversion of the MIR light to NIR light that is imaged using affordable, fast, and sensitive NIR detectors or camera...

Amplitude and frequency stabilized solid-state lasers in the near infrared

International Nuclear Information System (INIS)

Laporta, P.; Taccheo, S.; Marano, M.; Svelto, O.; Bava, E.; Galzerano, G.; Svelto, C.

2001-01-01

In this article we present a comprehensive review of the work done by our group on the amplitude and frequency stabilization of diode-pumped near-infrared solid-state lasers. In particular, we describe experiments based on single-mode Nd:YAG (1064 nm), Er-Yb:glass (1530-1560 nm), and Tm-Ho:YAG (2097 nm) lasers, end-pumped by semiconductor laser diodes. Amplitude stabilization is achieved by means of optoelectronic control loops sensing the laser intensity fluctuations and feeding back the error signal to the current of the pump diodes. Frequency stabilization is pursued using rovibrational molecular lines as absolute frequency references by means of various frequency locking techniques. The most interesting stability results are described in some detail whereas the wide literature cited through the paper provides for a useful reference list of related topics and experiments. (author)

Broadband Optical Active Waveguides Written by Femtosecond Laser Pulses in Lithium Fluoride

International Nuclear Information System (INIS)

Chiamenti, Ismael; Costa, Larissa N. da; Kalinowski, Hypolito J.; Bonfigli, Francesca; Montereali, Rosa Maria; Gomes Anderson, S. L.

2014-01-01

Broadband waveguiding through light-emitting strips directly written in a blank lithium fluoride crystal with a femtosecond laser is reported. Light guiding was observed at several optical wavelengths, from blue, 458 nm, to near-infrared, at 1550 nm. Visible photoluminescence spectra of the optically active F 2 and F 3 + color centers produced by the fs laser writing process were measured. The wavelength-dependent refractive index increase was estimated to be in the order of 10 −3 −10 −4 in the visible and near-infrared spectral intervals, which is consistent with the stable formation of point defects in LiF

Broadband Optical Active Waveguides Written by Femtosecond Laser Pulses in Lithium Fluoride

Science.gov (United States)

Ismael, Chiamenti; Francesca, Bonfigli; Anderson, S. L. Gomes; Rosa, Maria Montereali; Larissa, N. da Costa; Hypolito, J. Kalinowski

2014-01-01

Broadband waveguiding through light-emitting strips directly written in a blank lithium fluoride crystal with a femtosecond laser is reported. Light guiding was observed at several optical wavelengths, from blue, 458 nm, to near-infrared, at 1550 nm. Visible photoluminescence spectra of the optically active F2 and F3+ color centers produced by the fs laser writing process were measured. The wavelength-dependent refractive index increase was estimated to be in the order of 10-3-10-4 in the visible and near-infrared spectral intervals, which is consistent with the stable formation of point defects in LiF.

Infrared laser sealing of porcine vascular tissues using a 1,470 nm diode laser: Preliminary in vivo studies.

Science.gov (United States)

Cilip, Christopher M; Kerr, Duane; Latimer, Cassandra A; Rosenbury, Sarah B; Giglio, Nicholas C; Hutchens, Thomas C; Nau, William H; Fried, Nathaniel M

2017-04-01

Infrared (IR) lasers are being explored as an alternative to radiofrequency (RF) and ultrasonic (US) devices for rapid hemostasis with minimal collateral zones of thermal damage and tissue necrosis. Previously, a 1,470 nm IR laser sealed and cut ex vivo porcine renal arteries of 1-8 mm diameter in 2 seconds, yielding burst pressures greater than 1,200 mmHg and thermal coagulation zones less than 3 mm. This preliminary study describes in vivo testing of a handheld laser probe in a porcine model. A handheld prototype with vessel/tissue clasping mechanism was tested on 73 blood vessels less than 6 mm diameter using 1,470 nm laser power of 35 W for 1-5 seconds. Device power settings, irradiation time, tissue type, vessel diameter, and histology sample number were recorded for each procedure. The probe was evaluated for hemostasis after sealing isolated and bundled arteriole/venous (A/V) vasculature of porcine abdomen and hind leg. Sealed vessel samples were collected for histological analysis of lateral thermal damage. Hemostasis was achieved in 57 of 73 seals (78%). The probe consistently sealed vasculature in small bowel mesentery, mesometrium, and gastrosplenic and epiploic regions. Seal performance was less consistent on hind leg vasculature including saphenous arteries/bundles and femoral and iliac arteries. Collagen denaturation averaged 1.6 ± 0.9 mm in eight samples excised for histologic examination. A handheld laser probe sealed porcine vessels, in vivo. Further probe development and laser parameter optimization is necessary before infrared lasers may be evaluated as an alternative to RF and US vessel sealing devices. Lasers Surg. Med. 49:366-371, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Influences of Pinpoint Plantar Long-Wavelength Infrared Light Irradiation (Stress-Free Therapy on Chorioretinal Hemodynamics, Atherosclerosis Factors, and Vascular Endothelial Growth Factor

Directory of Open Access Journals (Sweden)

Keisou Ishimaru

2018-03-01

Full Text Available Background: We previously reported that pinpoint plantar long-wavelength infrared light irradiation (stress-free therapy; SFT is useful for alleviating insulin resistance and improving intracranial blood flow in patients with type 2 diabetes mellitus. This study was undertaken to evaluate the influences of SFT on chorioretinal hemodynamics (retinal artery and vein blood flows as well as atherosclerosis-related factors (TG, LDL-C and VEGF in patients with dyslipidemia. Methods: Four patients with dyslipidemia received 15-minute irradiation with a stress-free apparatus (far-infrared wavelength, 30 mW. Using laser speckle flowgraphy, associations of chorioretinal blood flow with peripheral atherosclerosis-inducing factors/VEGF levels before and after irradiation were analyzed. Results: Chorioretinal blood flow increased, while TG/LDL-C levels decreased, after irradiation. VEGF tended to rise in cases with pre-irradiation baseline levels at the lower limit but tended to decrease in cases in which baseline levels had exceeded the normal range. Conclusion: SFT was suggested to enhance chorioretinal circulation and to normalize VEGF, thereby possibly contributing to amelioration of atherosclerosis-inducing factors. Abnormalities in chorioretinal hemodynamics are known to be highly involved in the pathophysiology of diabetic retinopathy and age-related macular degeneration, and anti-VEGF antibody has been used for treating these conditions. The necessity of risk management, involving chorioretinal blood flow, has been pointed out when dealing with central retinal vein occlusion, diabetes mellitus, ischemic cerebral/cardiac disease, dementia and so on. SFT is therefore a potential complementary medical strategy which can be expected to contribute to normalization of chorioretinal blood flow and atherosclerosis-inducing factors/VEGF levels, and thereby to the prevention of lifestyle-related chronic diseases. Keywords: Pinpoint plantar long

Progress in metal-insulator-metal waveguide lasers at near-infrared wavelengths

NARCIS (Netherlands)

Marell, M.J.H.; Hill, M.T.

2009-01-01

Strong light con¯nement can be achieved in metallic cavities which can con¯ne light to volumes with dimensions considerably smaller than the wavelength of light. It was commonly believed, however, that the high losses in metals are prohibitive for laser peration in metallic nano-cavities. Recently

Investigation of rf plasma light sources for dye laser excitation

International Nuclear Information System (INIS)

Kendall, J.S.; Jaminet, J.F.

1975-06-01

Analytical and experimental studies were performed to assess the applicability of radio frequency (rf) induction heated plasma light sources for potential excitation of continuous dye lasers. Experimental efforts were directed toward development of a continuous light source having spectral flux and emission characteristics approaching that required for pumping organic dye lasers. Analytical studies were performed to investigate (1) methods of pulsing the light source to obtain higher radiant intensity and (2) methods of integrating the source with a reflective cavity for pumping a dye cell. (TFD)

Cutting efficiency of a mid-infrared laser on human enamel.

Science.gov (United States)

Levy, G; Koubi, G F; Miserendino, L J

1998-02-01

In this study, the cutting ability of a newly developed dental laser was compared with a dental high-speed handpiece and rotary bur for removal of enamel. Measurements of the volume of tissue removed, energy emitted, and time of exposure were used to quantify the ablation rate (rate of tissue removal) for each test group and compared. Cutting efficiency (mm3/s) of the laser was calculated based on the mean volume of tissue removed per pulse (mm3/pulse) and unit energy expended (mm3/J) over the range of applied powers (2, 4, 6, and 8 W). The specimens were then examined by light microscopy and scanning electron micrographs for qualitative analysis of the amount of remaining debris and the presence of the smear layer on the prepared enamel surface. Calculations of the cutting efficiency of the laser over the range of powers tested revealed a linear relationship with the level of applied power. The maximum average rate of tissue removal by the laser was 0.256 mm3/s at 8 W, compared with 0.945 mm3/s by the dental handpiece. Light microscopy and scanning electron micrograph examinations revealed a reduction in the amount of remaining debris and smear layer in the laser-prepared enamel surfaces, compared with the conventional method. Based on the results of this study, the cutting efficiency of the high-speed handpiece and dental bur was 3.7 times greater than the laser over the range of powers tested, but the laser appeared to create a cleaner enamel surface with minimal thermal damage. Further modifications of the laser system are suggested for improvement of laser cutting efficiency.

Laser tissue welding in ophthalmic surgery.

Science.gov (United States)

Rossi, Francesca; Matteini, Paolo; Ratto, Fulvio; Menabuoni, Luca; Lenzetti, Ivo; Pini, Roberto

2008-09-01

Laser welding of ocular tissues is an alternative technique or adjunct to conventional suturing in ophthalmic surgery. It is based on the photothermal interaction of laser light with the main components of the extracellular matrix of connective tissues. The advantages of the welding procedure with respect to standard suturing and stapling are reduced operation times, lesser inflammation, faster healing and increased ability to induce tissue regeneration. The procedure we set up is based on the use of an infrared diode laser in association with the topical application of the chromophore Indocyanine Green. Laser light may be delivered either continuously or in pulses, thus identifying two different techniques that have been applied clinically in various types of transplants of the cornea.

Gold nanocages covered by smart polymers for controlled release with near-infrared light

Science.gov (United States)

Yavuz, Mustafa S.; Cheng, Yiyun; Chen, Jingyi; Cobley, Claire M.; Zhang, Qiang; Rycenga, Matthew; Xie, Jingwei; Kim, Chulhong; Schwartz, Andrea G.; Wang, Lihong V.; Xia, Younan

2009-01-01

Photosensitive caged compounds have enhanced our ability to address the complexity of biological systems by generating effectors with remarkable spatial/temporal resolutions1-3. The caging effect is typically removed by photolysis with ultraviolet light to liberate the bioactive species. Although this technique has been successfully applied to many biological problems, it suffers from a number of intrinsic drawbacks. For example, it requires dedicated efforts to design and synthesize a precursor compound to the effector. The ultraviolet light may cause damage to biological samples and is only suitable for in vitro studies because of its quick attenuation in tissue4. Here we address these issues by developing a platform based on the photothermal effect of gold nanocages. Gold nanocages represent a class of nanostructures with hollow interiors and porous walls5. They can have strong absorption (for the photothermal effect) in the near-infrared (NIR) while maintaining a compact size. When the surface of a gold nanocage is covered with a smart polymer, the pre-loaded effector can be released in a controllable fashion using a NIR laser. This system works well with various effectors without involving sophiscated syntheses, and is well-suited for in vivo studies due to the high transparency of soft tissue in NIR6. PMID:19881498

[The influence of pulsed low-intensity laser radiation of the red (635 nm) and infrared (904 nm) spectra on the human mesenchymal stem cells in vitro].

Science.gov (United States)

Moskvin, S V; Kliuchnikov, D Iu; Antipov, E V; Volchkov, S E; Kiseleva, O N

2014-01-01

Mesenchymal stem cells (MSC) have for a long time been an object of investigation with a view to elucidating the prospects for their application in clinical medicine and cosmetology. One of the approaches to the non-specific regulation of the activity of these cells at the stage of preliminary in vitro combination is the treatment with low-intensity laser radiation (LILR). The objective of the present study was to evaluate the possibility of using pulsed LILR of the infrared and red spectra for this purpose. We used the 4th passage adhesive MSC cultures based at the umbilical tissue of a donor who gave the informed consent to participate in the study. The source of illumination was a Lazmik-VLOK laser therapeutic apparatus (RU No RZN 2014/1410 dated 06.02.2014) with the matrix laser infrared radiation heads (wavelength 904 nm, light pulse length 108 ns, frequency 1500 Hz). The apparatus was operated either in the multi-frequency Lazmik regime [Moskvin S.V., 2014] with mean power density 0.05 and 0.14 mW/cm2 and the red spectrum (wavelength 635 nm, light pulse length 144 ns, frequency 1500 Hz) or in the multi-frequency Lazmik regime [Moskvin S.V., 2014] with mean power density 0.03 and 0.12. The exposition was 5 min in both regimes. The study has demonstrated that neither the morphological structure nor the viability of mesenchymal stem cells changed under the influence of energy and time parameters used in experiments. The number of cells was shown to slightly increase in comparison with control. The most pronounced effect was documented after illumination with pulse infrared (904 nm) LILR in the multi-frequency Lazmik regime. The maximum effect was observed during a period between days 1 and 3 of cultivation.

Biological infrared microspectroscopy at the National Synchrotron Light Source

International Nuclear Information System (INIS)

Miller, Lisa M.; Carr, G. Lawrence; Williams, Gwyn P.; Sullivan, Michael; Chance, Mark R.

2000-01-01

Beamline U2B at the National Synchrotron Light Source has been designed and built as an infrared beamline dedicated to the study of biomedical problems. In 1997, the horizontal and vertical acceptances of Beamline U2B were increased in order to increase the overall flux of the beamline. A wedged, CVD diamond window separates the UHV vacuum of the VUV ring from the rough vacuum of the beamline. The endstation consists of a Nicolet Magna 860 step-scan FTIR and a NicPlan infrared microscope. The spectrometer is equipped with beamsplitter/detector combinations that permit data collection in the mid-and far-infrared regions. We have also made provisions for mounting an external detector (e.g. bolometer) for far infrared microspectroscopy. Thus far, Beamline U2B has been used to (1) perform chemical imaging of bone tissue and brain cells to address issues related to bone disease and epilepsy, respectively, and (2) examine time-resolved protein structure in the sub-millisecond folding of cytochrome c

The 'Magic Light': A Discussion on Laser Ethics.

Science.gov (United States)

Stylianou, Andreas; Talias, Michael A

2015-08-01

Innovations in technology and science form novel fields that, although beneficial, introduce new bio-ethical issues. In their short history, lasers have greatly influenced our everyday lives, especially in medicine. This paper focuses particularly on medical and para-medical laser ethics and their origins, and presents the complex relationships within laser ethics through a three-dimensional matrix model. The term 'laser' and the myth of the 'magic light' can be identified as landmarks for laser related ethical issues. These ethical issues are divided into five major groups: (1) media, marketing, and advertising; (2) economic outcomes; (3) user training; (4) the user-patient/client relationship; and (5) other issues. In addition, issues arising from two of the most common applications of lasers, laser eye surgery and laser tattoo removal, are discussed. The aim of this paper is to demonstrate that the use of medical and para-medical lasers has so greatly influenced our lives that the scientific community must initiate an earnest discussion of medical laser ethics.

Laser-induced down-conversion and infrared phosphorescence emissivity of novel ligand-free perovskite nanomaterials

Science.gov (United States)

Ahmed, M. A.; Khafagy, Rasha M.; El-sayed, O.

2014-03-01

For the first time, standalone and ligand-free series of novel rare-earth-based perovskite nanomaterials are used as near infrared (NIR) and mid infrared (MIR) emitters. Nano-sized La0.7Sr0.3M0.1Fe0.9O3; where M = 0, Mn2+, Co2+ or Ni2+ were synthesized using the flash auto-combustion method and characterized using FTIR, FT-Raman, SEM and EDX. Photoluminescence spectra were spontaneously recorded during pumping the samples with 0.5 mW of green laser emitting continuously at 532 nm. La0.7Sr0.3FeO3 (where M = 0) did not result in any infrared emissivity, while intense near and mid infrared down-converted phosphorescence was released from the M-doped samples. The released phosphorescence greatly shifted among the infrared spectral region with changing the doping cation. Ni2+-doped perovskite emitted at the short-wavelength near-infrared region, while Mn2+ and Co2+-doped perovskites emitted at the mid-wavelength infrared region. The detected laser-induced spontaneous parametric down-conversion phosphorescence (SPDC) occurred through a two-photon process by emitting two NIR or MIR photons among a cooperative energy transfer between the La3+ cations and the M2+ cations. Combining SrFeO3 ceramic with both a rare earth cation (RE3+) and a transition metal cation (Mn2+, Co2+ or Ni2+), rather than introducing merely RE3+ cations, greatly improved and controlled the infrared emissivity properties of synthesized perovskites through destroying their crystal symmetry and giving rise to asymmetrical lattice vibration and the nonlinear optical character. The existence of SPDC in the M2+-doped samples verifies their nonlinear character after the absence of this character in La0.7Sr0.3FeO3. Obtained results verify that, for the first time, perovskite nanomaterials are considered as nonlinear optical crystals with intense infrared emissivity at low pumping power of visible wavelengths, which nominates them for photonic applications and requires further studies regarding their lasing

High coupling efficiency of foam spherical hohlraum driven by 2ω laser light

Science.gov (United States)

Chen, Yao-Hua; Lan, Ke; Zheng, Wanguo; Campbell, E. M.

2018-02-01

The majority of solid state laser facilities built for laser fusion research irradiate targets with third harmonic light (0.35 μm) up-converted from the fundamental Nd wavelength at 1.05 μm. The motivation for this choice of wavelength is improved laser-plasma coupling. Significant disadvantages to this choice of wavelength are the reduced damage threshold of optical components and the efficiency of energy conversion to third harmonic light. Both these issues are significantly improved if second harmonic (0.53 μm) radiation is used, but theory and experiments have shown lower optical to x-ray energy conversion efficiency and increased levels of laser-plasma instabilities, resulting in reduced laser-target coupling. In this letter, we propose to use a 0.53 μm laser for the laser ignition facilities and use a low density foam wall to increase the coupling efficiency from the laser to the capsule and present two-dimensional radiation-hydrodynamic simulations of 0.53 μm laser light irradiating an octahedral-spherical hohlraum with a low density foam wall. The simulations show that the reduced optical depth of the foam wall leads to an increased laser-light conversion into thermal x-rays and about 10% higher radiation flux on the capsule than that achieved with 0.35 μm light irradiating a solid density wall commonly used in laser indirect drive fusion research. The details of the simulations and their implications and suggestions for wavelength scaling coupled with innovative hohlraum designs will be discussed.

Application and possible mechanisms of combining LLLT (low level laser therapy), infrared hyperthermia and ionizing radiation in the treatment of cancer

Science.gov (United States)

Abraham, Edward H.; Woo, Van H.; Harlin-Jones, Cheryl; Heselich, Anja; Frohns, Florian

2014-02-01

Benefit of concomitant infrared hyperthermia and low level laser therapy and ionizing radiation is evaluated in this study. The purpose/objectives: presentation with locally advanced bulky superficial tumors is clinically challenging. To enhance the efficacy of chemotherapy and IMRT (intensity-modulated radiation therapy) and/or electron beam therapy we have developed an inexpensive and clinically effective infrared hyperthermia approach that combines black-body infrared radiation with halogen spectrum radiation and discrete wave length infrared clinical lasers LLLT. The goal is to produce a composite spectrum extending from the far infrared to near infrared and portions of the visible spectrum with discrete penetrating wavelengths generated by the clinical infrared lasers with frequencies of 810 nm and/or 830 nm. The composite spectrum from these sources is applied before and after radiation therapy. We monitor the surface and in some cases deeper temperatures with thermal probes, but use an array of surface probes as the limiting safe thermal constraint in patient treatment while at the same time maximizing infrared entry to deeper tissue layers. Fever-grade infrared hyperthermia is produced in the first centimeters while non-thermal infrared effects act at deeper tissue layers. The combination of these effects with ionizing radiation leads to improved tumor control in many cancers.

Spectral blueshifts in laser light scattered from argon-gas-cluster plasmas

International Nuclear Information System (INIS)

Singhal, H.; Arora, V.; Naik, P.A.; Gupta, P.D.

2005-01-01

An experimental study is presented on scattering of laser light from argon gas clusters irradiated by multipicosecond Nd:glass laser pulses at moderate intensity of 10 15 W/cm 2 . Space-resolved side-scattered laser light has a predominantly blueshifted and broadened spectrum (up to ∼8 nm). The scattered signal intensity and average blueshift exhibit a marked dependence on the backing pressure of the gas. The results are explained by self-phase modulation of the laser radiation due to changing polarizability as the heated clusters pass through resonance at 3 times the critical density during which intense absorption and scattering occurs. The observed blueshift may be useful in diagnostics of this important phase of laser-cluster interactions

Direct pumping of ultrashort Ti:sapphire lasers by a frequency doubled diode laser

DEFF Research Database (Denmark)

Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika

2011-01-01

electro-optical efficiency of the diode laser. Autocorrelation measurements show that pulse widths of less than 20 fs can be expected with an average power of 52 mW when using our laser. These results indicate the high potential of direct diode laser pumped Ti: sapphire lasers to be used in applications....... When using our diode laser system, the optical conversion efficiencies from green to near-infrared light reduces to 75 % of the values achieved with the commercial pump laser. Despite this reduction the overall efficiency of the Ti: sapphire laser is still increased by a factor > 2 due to the superior...... like retinal optical coherence tomography (OCT) or pumping of photonic crystal fibers for CARS (coherent anti-stokes Raman spectroscopy) microscopy....

Acute effects of vascular modifying agents in solid tumors assessed by noninvasive laser Doppler flowmetry and near infrared spectroscopy

DEFF Research Database (Denmark)

Kragh, Michael; Quistorff, Bjørn; Horsman, Michael R

2002-01-01

LDF, using a 41 degrees C heated custom-built LDF probe with four integrated laser/receiver units, and tumor blood volume was estimated by NIRS, using light guide coupled reflectance measurements at 800+/-10 nm. FAA, DMXAA, CA4DP, and HDZ significantly decreased tumor perfusion by 50%, 47%, 73......The potential of noninvasive laser Doppler flowmetry (LDF) and near infrared spectroscopy (NIRS) to detect acute effects of different vascular-modifying agents on perfusion and blood volume in tumors was evaluated. C3H mouse mammary carcinomas (approximately 200 mm(3)) in the rear foot of CDF1 mice......%, and 78%, respectively. In addition, FAA, DMXAA, and HDZ significantly reduced the blood volume within the tumor, indicating that these compounds to some degree shunted blood from the tumor to adjacent tissue, HDZ being most potent. CA4DP caused no change in the tumor blood volume, indicating...

Control strategies for laser separation of carbon isotopes

Indian Academy of Sciences (India)

Laser isotope separation (LIS) by infrared laser chemistry of polyatomic molecules has come a long way since its discovery. The last decade has seen considerable efforts in scaling up of the process for light elements like carbon, oxygen and silicon. These efforts aim at ways to improve both the enrichment factor and the ...

Spatial temperature distribution in human hairy and glabrous skin after infrared CO2 laser radiation

DEFF Research Database (Denmark)

Frahm, Ken Steffen; Andersen, Ole K.; Arendt-Nielsen, Lars

2010-01-01

Background: CO(2) lasers have been used for several decades as an experimental non-touching pain stimulator. The laser energy is absorbed by the water content in the most superficial layers of the skin. The deeper located nociceptors are activated by passive conduction of heat from superficial...... to deeper skin layers. Methods: In the current study, a 2D axial finite element model was developed and validated to describe the spatial temperature distribution in the skin after infrared CO(2) laser stimulation. The geometry of the model was based on high resolution ultrasound scans. The simulations were...... compared to the subjective pain intensity ratings from 16 subjects and to the surface skin temperature distributions measured by an infrared camera. Results: The stimulations were sensed significantly slower and less intense in glabrous skin than they were in hairy skin (MANOVA, p

Luminescence from potassium feldspars stimulated by infrared and green light

DEFF Research Database (Denmark)

Duller, G.A.T.; Bøtter-Jensen, L.

1993-01-01

A series of experiments are reported which investigate stimulated luminescence from potassium feldspar. The aim is to provide a basic phenomenological description of the response of the material to stimulation by heat, infrared radiation (875 DELTA 80 nm) and a green light wavelength band from 5 15...... to 560 nm. Two conclusions are drawn: firstly it is suggested that the majority of the trapped charge responsible for the infrared stimulated luminescence signal does not give rise to a thermoluminescence signal, and secondly that a large traction of the two optically stimulated luminescence signals...

3D features of modified photostructurable glass-ceramic with infrared femtosecond laser pulses

Energy Technology Data Exchange (ETDEWEB)

Fernandez-Pradas, J.M., E-mail: jmfernandez@ub.edu [Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Marti i Franques 1, E-08028 Barcelona (Spain); Serrano, D.; Bosch, S.; Morenza, J.L.; Serra, P. [Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Marti i Franques 1, E-08028 Barcelona (Spain)

2011-04-01

The exclusive ability of laser radiation to be focused inside transparent materials makes lasers a unique tool to process inner parts of them unreachable with other techniques. Hence, laser direct-write can be used to create 3D structures inside bulk materials. Infrared femtosecond lasers are especially indicated for this purpose because a multiphoton process is usually required for absorption and high resolution can be attained. This work studies the modifications produced by 450 fs laser pulses at 1027 nm wavelength focused inside a photostructurable glass-ceramic (Foturan) at different depths. Irradiated samples were submitted to standard thermal treatment and subsequent soaking in HF solution to form the buried microchannels and thus unveil the modified material. The voxel dimensions of modified material depend on the laser pulse energy and the depth at which the laser is focused. Spherical aberration and self-focusing phenomena are required to explain the observed results.

Optical-fiber-based laser-induced breakdown spectroscopy for detection of early caries

Science.gov (United States)

Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

2015-06-01

A laser-induced breakdown spectroscopy (LIBS) system targeting for the in vivo analysis of tooth enamel is described. The system is planned to enable real-time analysis of teeth during laser dental treatment by utilizing a hollow optical fiber that transmits both Q-switched Nd:YAG laser light for LIBS and infrared Er:YAG laser light for tooth ablation. The sensitivity of caries detection was substantially improved by expanding the spectral region under analysis to ultraviolet (UV) light and by focusing on emission peaks of Zn in the UV region. Subsequently, early caries were distinguished from healthy teeth with accuracy rates above 80% in vitro.

Photosynthesis-related infrared light transmission changes in spinach leaf segments

International Nuclear Information System (INIS)

Akimoto, T.

1985-01-01

The time courses of infrared light transmission changes and fluorescence induced by light in spinach leaf segments were measured. The illumination by red light exhibited a complex wave pattern. The transmission approached the baseline after repeating decreases and increases. Illumination by far-red light decreased the transmission. One of the differences between the two responses was the difference between the two amplitudes of the first increasing component. The component in the red light response was larger than the component in the far-red light response. The transmission decrease by far-red light is supposed to correspond to ''red drop.'' The transmission decrease by far-red light was suppressed by red light. This is due to an activation of a transmission-increasing component. This probably corresponds to ''enhancement.'' A proportional correlation existed between the intensity of far-red light and the minimum intensity of red light that suppressed the transmission decrease induced by far-red light. The component which made Peak D in the time course of fluorescence yield and the first increasing component in the transmission changes were suppressed by intense light

High-pressure synchrotron infrared spectroscopy at the National Synchrotron Light Source

International Nuclear Information System (INIS)

Hemley, R.J.; Goncharov, A.F.; Lu, R.; Struzhkin, V.V.; Li, M.; Mao, H.K.

1998-01-01

The paper describes a synchrotron infrared facility for high-pressure spectroscopy and microspectroscopy at the National Synchrotron Light-Source (NSLS). Located at beamline U2B on the VUV ring of the NSLS, the facility utilizes a commercial FT-IR together with custom-built microscope optics designed for a variety of diamond anvil cell experiments, including low- and high- temperature studies. The system contains an integrated laser optical/grating spectrometer for concurrent optical experiments. The facility has been used to characterize a growing number of materials to ultrahigh pressure and has been instrumental of new high-pressure phenomena. Experiments on dense hydrogen to >200 GPa have led to the discovery of numerous unexpected properties of this fundamental system. The theoretically predicted molecular-atomic transition of H 2 O ice to the symmetric hydrogen-bonded structure has been identified, and new classes of high-density clathrates and molecular compounds have been characterized. Experiments on natural and synthetic mineral samples have been performed to study hydrogen speciation, phase transformations, and microscopic inclusions in multiphase assemblages. Detailed information on the behavior of new materials, including novel high-pressure glasses and ceramics, has also been obtained

Alignment control of columnar liquid crystals with wavelength tunable CO2 laser irradiation

International Nuclear Information System (INIS)

Monobe, Hirosato; Awazu, Kunio; Shimizu, Yo

2008-01-01

Infrared-induced alignment change with wavelength tunable CO 2 laser irradiation for columnar liquid crystal domains was investigated for a liquid crystalline triphenylene derivative. A uniformly aligned alignment change of domains was observed when a chopped linearly polarized infrared laser light corresponding to the wavelength of the aromatic C-O-C stretching vibration band (9.65 μm) was irradiated. The results strongly imply that the infrared irradiation is a possible technique for device fabrication by use of columnar mesophase as a liquid crystalline semiconductor

Suppressed speckle contrast of blue light emission out of white lamp with phosphors excited by blue laser diodes for high-brightness lighting applications

Science.gov (United States)

Kinoshita, Junichi; Ikeda, Yoshihisa; Takeda, Yuji; Ueno, Misaki; Kawasaki, Yoji; Matsuba, Yoshiaki; Heike, Atsushi

2012-11-01

The speckle contrast of blue light emission out of high-brightness white lamps using phosphors excited by InGaN/GaN blue laser diodes is evaluated as a measure of coherence. As a result, speckle contrast of as low as 1.7%, the same level as a blue light emitting diode, is obtained. This implies that the original blue laser light can be converted into incoherent light through lamp structures without any dynamic mechanisms. This unique speckle-free performance is considered to be realized by multiple scattering inside the lamp structure, the multi-longitudinal mode operation of the blue laser diodes, and the use of multiple laser diodes. Such almost-incoherent white lamps can be applied for general lighting without any nuisance of speckle noise and should be categorized as lamps rather than lasers in terms of laser safety regulation.

Application of mid-infrared tuneable diode laser absorption spectroscopy to plasma diagnostics: a review

International Nuclear Information System (INIS)

Roepcke, J; Lombardi, G; Rousseau, A; Davies, P B

2006-01-01

Within the last decade mid-infrared absorption spectroscopy over a region from 3 to 17μm and based on tuneable lead salt diode lasers, often called tuneable diode laser absorption spectroscopy or TDLAS, has progressed considerably as a powerful diagnostic technique for in situ studies of the fundamental physics and chemistry in molecular plasmas. The increasing interest in processing plasmas containing hydrocarbons, fluorocarbons, organo-silicon and boron compounds has led to further applications of TDLAS because most of these compounds and their decomposition products are infrared active. TDLAS provides a means of determining the absolute concentrations of the ground states of stable and transient molecular species, which is of particular importance for the investigation of reaction kinetic phenomena. Information about gas temperature and population densities can also be derived from TDLAS measurements. A variety of free radicals and molecular ions have been detected by TDLAS. Since plasmas with molecular feed gases are used in many applications such as thin film deposition, semiconductor processing, surface activation and cleaning, and materials and waste treatment, this has stimulated the adaptation of infrared spectroscopic techniques to industrial requirements. The recent development of quantum cascade lasers (QCLs) offers an attractive new option for the monitoring and control of industrial plasma processes. The aim of the present paper is threefold: (i) to review recent achievements in our understanding of molecular phenomena in plasmas (ii) to report on selected studies of the spectroscopic properties and kinetic behaviour of radicals and (iii) to describe the current status of advanced instrumentation for TDLAS in the mid-infrared

Using a helium--neon laser to convert infrared radiation to visible emission on lithium niobate crystals

Energy Technology Data Exchange (ETDEWEB)

Aurtyunyan, E.A.; Kostanyan, R.B.; Mkrtchyan, V.S.; Mkrtchyan, M.A.

1975-01-01

The conversion of infrared emission to the visible region was investigated by mixing with helium-neon laser emission in lithium niobate crystals. The infrared source was a Globar, and the laser was the LG-75. Emission of the sum frequencies was filtered out. The spectral composition of the converted radiation was analyzed by the ISP-51 spectrograph with an FEU-79 photomultiplier at the output. The amplified photomultiplier signal was recorded by the ChZ-33 frequency meter. By varying the angle between the optical axis of the crystal and the incident emission, infrared radiation in the 1.75 to 3.3 ..mu..m wavelength band could be converted to visible emission. It is suggested that measurement of the wavelength of converted emission might be used to study the distribution of concentration nonhomogeneities in crystals.

Design and construction of liquid lasers using organic dyes

International Nuclear Information System (INIS)

Hariri, Akbar.

1984-01-01

Organic dye solution show great promise of obtaining tunable coherent light over the uv, visible and near infrared portion of spectrum. In this paper we describe various pumping schemes of dye molecules. Design, construction and performance of a pulsed dye laser, transversely pumped by a nitrogen laser and wall-ablation flash lamp-pumped dye lasers are the particular examples which are presented in detail

Flaw evaluation of Nd:YAG laser welding based plume shape by infrared thermal camera

International Nuclear Information System (INIS)

Kim, Jae Yeol; Yoo, Young Tae; Yang, Dong Jo; Song, Kyung Seol; Ro, Kyoung Bo

2003-01-01

In Nd:YAG laser welding evaluation methods of welding flaw are various. But, the method due to plume shape is difficult to classification od welding flaw. The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. At the present time, some methods are studied for measurement of plume shape by using high-speed camera and photo diode. This paper describes the machining characteristics of SM45C carbon steel welding by use of an Nd:YAG laser. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. In this study, plume shape was measured by infrared thermal camera that is non-contact/non-destructive thermal measurement equipment through change of laser generating power, speed, focus. Weld was performed on bead-on method. Measurement results are compared as two equipment. Here, two results are composed of measurement results of plume quantities due to plume shape by infrared thermal camera and inspection results of weld bead include weld flaws by ultrasonic inspector.

Laser light scattering in Brownian medium

International Nuclear Information System (INIS)

Suwono; Santoso, Budi; Baiquni, A.

1983-01-01

The principle of laser light scattering in Brownian medium and photon correlation spectroscopy are described in detail. Their application to the study of the behaviour of a polystyrene latex solution are discussed. The auto-correlation function of light scattered by the polystyrene latex solution in various angle, various temperature and in various sample times, have been measured. Information on the translation diffusion coefficient and size on the particle can be obtained from the auto-correlation function. Good agreement between the available data and experiment is shown. (author)

The role of lasers and intense pulsed light technology in dermatology

Science.gov (United States)

Husain, Zain; Alster, Tina S

2016-01-01

The role of light-based technologies in dermatology has expanded dramatically in recent years. Lasers and intense pulsed light have been used to safely and effectively treat a diverse array of cutaneous conditions, including vascular and pigmented lesions, tattoos, scars, and undesired hair, while also providing extensive therapeutic options for cosmetic rejuvenation and other dermatologic conditions. Dermatologic laser procedures are becoming increasingly popular worldwide, and demand for them has fueled new innovations and clinical applications. These systems continue to evolve and provide enhanced therapeutic outcomes with improved safety profiles. This review highlights the important roles and varied clinical applications that lasers and intense pulsed light play in the dermatologic practice. PMID:26893574

Manipulation of gene expression by infrared laser heat shock and its application to the study of tracheal development in Drosophila.

Science.gov (United States)

Miao, Guangxia; Hayashi, Shigeo

2015-03-01

Induction of gene expression in a specific cell and a defined time window is desirable to investigate gene function at the cellular level during morphogenesis. To achieve this, we attempted to introduce the infrared laser-evoked gene operator system (IR-LEGO, Kamei et al., 2009) in the Drosophila embryo. In this technique, infrared laser light illumination induces genes to be expressed under the control of heat shock promoters at the single cell level. We applied IR-LEGO to a transgenic fly stock, HS-eGFP, in which the enhanced green fluorescent protein (eGFP) gene is placed under the control of heat shock protein 70 promoter, and showed that eGFP expression can be induced in single cells within 1-2 hr after IR illumination. Furthermore, induction of HS-Branchless transgene encoding the Drosophila fibroblast growth factor (FGF) effectively altered the migration and branching patterns of the tracheal system. Our results indicated that IR-LEGO is a promising choice for the timely control of gene expression in a small group of cells in the Drosophila embryo. By using IR-LEGO, we further demonstrated that the tracheal terminal branching program is sensitive to localized expression of exogenous FGF. © 2014 Wiley Periodicals, Inc.

Nonlinear frequency conversion in fiber lasers

DEFF Research Database (Denmark)

Svane, Ask Sebastian

The concept of nonlinear frequency conversion entails generating light at new frequencies other than those of the source light. The emission wavelength of typical fiber laser systems, relying on rare-earth dopants, are constrained within specific bands of the infrared region. By exploiting...... nonlinear processes, light from these specific wavelength bands can be used to generate light at new frequencies otherwise not obtainable by rare-earth elements. This thesis describes work covering Raman fiber lasers (RFLs) and amplifiers for nonlinear frequency down-conversion, and also the method...... of fiberoptic Cherenkov radiation (FCR) using ultrafast pulses as a means for generating tunable visible (VIS) light at higher frequencies. Two different polarization maintaining (PM) RFL cavities are studied with an emphasis on stability and spectral broadening. The cavities are formed by inscription of fiber...

Investigation of saturation effects in ceramic phosphors for laser lighting

DEFF Research Database (Denmark)

Krasnoshchoka, Anastasiia; Thorseth, Anders; Dam-Hansen, Carsten

2017-01-01

We report observation of saturation effects in a Ce:LuAG and Eu-doped nitride ceramic phosphor for conversion of blue laser light for white light generation. The luminous flux from the phosphors material increases linearly with the input power until saturation effects limit the conversion....... It is shown, that the temperature of the phosphor layer influences the saturation power level and the conversion efficiency. It is also shown that the correlated color temperature (CCT), phosphor conversion efficiency and color rendering index (CRI) are dependent both on incident power and spot size diameter...... of the illumination. A phosphor conversion efficiency up to 140.8 lm/W with CRI of 89.4 was achieved. The saturation in a ceramic phosphor, when illuminated by high intensity laser diodes, is estimated to play the main role in limiting the available luminance from laser based lighting systems....

Spectrum of reflected light by self-focusing of light in a laser plasma

International Nuclear Information System (INIS)

Gorbunov, L.M.

1983-01-01

The spectrum of the radiation reflected by a laser-produced plasma is considered. In this situation, self-focusing occurs and a region of low density (caviton) is formed. It is shown that the process leads to a considerable broadening of the spectrum on the ''red'' side, and to the appearance of a line structure in the spectrum. The results can explain data for the reflected light spectrum [L. M. Gorbunov et al., FIAN Preprint No. 126 (1979)] as being due to the nonstationary self-focusing of light in a laser-produced plasma that has recently been observed [V. L. Artsimovich et al., FIAN Preprint No. 252 (1981); Sov. Phys. Doklady 27, 618 (1982)

The laser: a concentrate of light. From the creation of a beam to its applications

International Nuclear Information System (INIS)

2005-04-01

The first lasers were developed in the 1960's. The name LASER is an acronym for 'Light Amplification by the Stimulated Emission of Radiation'. The almost magical properties of laser light soon led to their use in a variety of applications. We use lasers every day in our CD players and in the bar-code readers used in supermarkets. Laser light shows create beautiful patterns of light in the air. Lasers are also precision workers in industry. They are used to cut, weld and drill materials. They are used in medicine to repair or burn away diseased tissue without harming healthy tissue nearby. Straight and narrow laser beams are also used to align roads and tunnels. But why is it that lasers can do all these things while ordinary light from the Sun or from a light bulb cannot? 'Lasers are everywhere - in medicine, in industry, and at the heart of our daily lives'. CEA has worked on all types of lasers for many years. CEA researchers use them in their work in all the traditional ways (alignment, drilling, welding, cutting, etc.), but they also develop new types of lasers for specific applications. They use very high power lasers to study the interaction between high energies and matter. Lasers are essential tools in many applications, but we must never forget the risks that are associated with them. The CEA is studying the effects of lasers on the body. There is still much research to be done in the field of laser technology. We expect more and more applications in the next few years. (authors)

Blue laser diode (LD) and light emitting diode (LED) applications

International Nuclear Information System (INIS)

Bergh, Arpad A.

2004-01-01

The family of blue LEDs, edge emitting and surface emitting lasers, enable a number of applications. Blue lasers are used in digital applications such as optical storage in high density DVDs. The resolution of the spot size and hence the storage density is diffraction limited and is inversely proportional to the square of the wavelength of the laser. Other applications include printing, optical scanners, and high-resolution photo-lithography. As light emitters, blue LEDs are used for signaling and in direct view large area emissive displays. They are also making inroads into signage and LCD back-lighting, mobile platforms, and decorative accent lighting in curtains, furniture, etc. Blue LEDs produce white light either with phosphor wavelength converters or in combination with red and green LEDs. The full potential of LED light sources will require three devices to enable complete control over color and intensity. Sensing and medical/bio applications have a major impact on home security, on monitoring the environment, and on health care. New emerging diagnostic and therapeutic applications will improve the quality and reduce the cost of health care. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Blue laser diode (LD) and light emitting diode (LED) applications

Energy Technology Data Exchange (ETDEWEB)

Bergh, Arpad A [Optoelectronics Industry Development Association (OIDA), 1133 Connecticut Avenue, NW, Suite 600, Washington, DC 20036-4329 (United States)

2004-09-01

The family of blue LEDs, edge emitting and surface emitting lasers, enable a number of applications. Blue lasers are used in digital applications such as optical storage in high density DVDs. The resolution of the spot size and hence the storage density is diffraction limited and is inversely proportional to the square of the wavelength of the laser. Other applications include printing, optical scanners, and high-resolution photo-lithography. As light emitters, blue LEDs are used for signaling and in direct view large area emissive displays. They are also making inroads into signage and LCD back-lighting, mobile platforms, and decorative accent lighting in curtains, furniture, etc. Blue LEDs produce white light either with phosphor wavelength converters or in combination with red and green LEDs. The full potential of LED light sources will require three devices to enable complete control over color and intensity. Sensing and medical/bio applications have a major impact on home security, on monitoring the environment, and on health care. New emerging diagnostic and therapeutic applications will improve the quality and reduce the cost of health care. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Infrared and visible laser spectroscopy for highly-charged Ni-like ions

Science.gov (United States)

Ralchenko, Yuri

2017-10-01

Application of visible or infrared (IR) lasers for spectroscopy of highly-charged ions (HCI) has not been particularly extensive so far due to a mismatch in typical energies. We show here that the energy difference between the two lowest levels within the first excited configuration 3d9 4 s in Ni-like ions of heavy elements from ZN = 60 to ZN = 92 is within the range of visible or near-IR lasers. The wavelengths of these transitions are calculated within the relativistic model potential formalism and compared with other theoretical and limited experimental data. Detailed collisional-radiative simulations of non-Maxwellian and thermal plasmas are performed showing that photopumping between these levels using relatively moderate lasers is sufficient to provide a two-order of magnitude increase of the pumped level population. This accordingly results in a similar rise of the X-ray line intensity thereby allowing control of X-ray emission with visible/IR lasers.

The design and development of CO2 medium-level laser power calibration system for industrial and medical applications in Thailand

Science.gov (United States)

Nontapot, Kanokwan

2018-03-01

The carbon dioxide laser (CO2 laser) is one of the most useful and is the highest CW laser at the present. The laser produces infrared light at 10.6 um. Due to its high power, CO2 lasers are usually used in industrial applications such as cutting and welding, or for engraving at less power. CO2 lasers are also used widely in medical applications, such as laser surgery, skin resurfacing, and removing mold, due to water (biological tissue) absorb light at this wavelength very well. CO2 lasers are also used as LIDAR laser source for military range finding applications because of the transparency of the atmosphere to infrared light. Due to the increasing use of CO2 lasers laser in industrial and medical applications in Thailand, the National Institute of Metrology (Thailand) has set up a CO2 laser power calibration system and provide calibration service to customers this year. The service support calibration of medium-level laser power at wavelength of 10.6 um and at power range 100 mW-10W. The design and development of the calibration system will be presented.

Patient identification using a near-infrared laser scanner

Science.gov (United States)

Manit, Jirapong; Bremer, Christina; Schweikard, Achim; Ernst, Floris

2017-03-01

We propose a new biometric approach where the tissue thickness of a person's forehead is used as a biometric feature. Given that the spatial registration of two 3D laser scans of the same human face usually produces a low error value, the principle of point cloud registration and its error metric can be applied to human classification techniques. However, by only considering the spatial error, it is not possible to reliably verify a person's identity. We propose to use a novel near-infrared laser-based head tracking system to determine an additional feature, the tissue thickness, and include this in the error metric. Using MRI as a ground truth, data from the foreheads of 30 subjects was collected from which a 4D reference point cloud was created for each subject. The measurements from the near-infrared system were registered with all reference point clouds using the ICP algorithm. Afterwards, the spatial and tissue thickness errors were extracted, forming a 2D feature space. For all subjects, the lowest feature distance resulted from the registration of a measurement and the reference point cloud of the same person. The combined registration error features yielded two clusters in the feature space, one from the same subject and another from the other subjects. When only the tissue thickness error was considered, these clusters were less distinct but still present. These findings could help to raise safety standards for head and neck cancer patients and lays the foundation for a future human identification technique.

Control of the droplet generation by an infrared laser

Directory of Open Access Journals (Sweden)

Zhibin Wang

2018-01-01

Full Text Available In this work, the control of the droplet generation by a focused infrared (IR laser with a wavelength of 1550 nm was studied, in which the liquid water and the oil with the surfactant of Span 80 were employed as the disperse and continuous phases, respectively. The characteristics of the droplet generation controlled by the laser was explored under various flow rates, laser powers and spot positions and the comparison between the cases with/without the laser was also performed. The results showed that when the laser was focused on the region away from the outlet of the liquid water inflow channel, the droplet shedding was blocked due to the IR laser heating induced thermocapillary flow, leading to the increase of the droplet volume and the cycle time of the droplet generation as compared to the case without the laser. Decreasing the continuous phase flow rate led to the increase of the droplet volume, cycle time of the droplet generation and the volume increase ratio, while increasing the disperse phase flow rate led to the increase of the droplet volume and the decrease of the cycle time and volume increase ratio. For a given flow rate ratio between the continuous and disperse phases, the increase of the flow rates decreased the volume increase ratio. In addition, it is also found that the droplet volume, the cycle time and the volume increase ratio all increased with the laser power. When the laser was focused at the inlet of the downstream channel, the droplet volume, the cycle time and the volume increase ratio were the largest. Moving the laser spot to the downstream or upstream led to the decrease of them. When the laser was focused on the outlet of the liquid water inflow channel, the generated droplet volume and cycle time of the droplet generation were even lower than the case without the laser because of the lowered viscosity. This works provides a comprehensive understanding of the characteristics of the droplet generation controlled

Basic study of charring detection at the laser catheter-tip using back scattering light measurement during therapeutic laser irradiation in blood.

Science.gov (United States)

Takahashi, Mei; Ito, Arisa; Kajihara, Takuro; Matsuo, Hiroki; Arai, Tsunenori

2010-01-01

The purpose of this study is to investigate transient process of the charring at the laser catheter-tip in blood during therapeutic laser irradiation by the back scattering light measurement to detect precursor state of the charring. We took account of using photodynamic therapy for arrhythmia in blood through the laser catheter. We observed the influence of the red laser irradiation (λ=663 nm) upon the shape of red blood cells (RBCs). The RBCs aggregation, round formation, and hemolysis were took place sequentially before charring. With a model blood sandwiched between glass plates simulated as a catheter-tip boundary, we measured diffuse-reflected-light power and transmitted-light power simultaneously and continuously by a microscopic optics during the laser irradiation. We found that measured light power changes were originated with RBCs shape change induced by temperature rise due to the laser irradiation. A gentle peak following a slow descending was observed in the diffuse-reflected-light power history. This history might indicate the precursor state of the charring, in which the hemolysis might be considered to advance rapidly. We think that the measurement of diffuse-reflected-light power history might be able to detect precursor state of charring at the catheter-tip in blood.

Ions and light

CERN Document Server

Bowers, Michael T

2013-01-01

Gas Phase Ion Chemistry, Volume 3: Ions and Light discusses how ions are formed by electron impact, ion-molecule reactions, or electrical discharge. This book discusses the use of light emitted by excited molecules to characterize either the chemistry that formed the excited ion, the structure of the excited ion, or both.Organized into 10 chapters, this volume begins with an overview of the extension of the classical flowing afterglow technique to include infrared and chemiluminescence and laser-induced fluorescence detection. This text then examines the experiments involving molecules that ar

Laterally injected light-emitting diode and laser diode

Science.gov (United States)

Miller, Mary A.; Crawford, Mary H.; Allerman, Andrew A.

2015-06-16

A p-type superlattice is used to laterally inject holes into an III-nitride multiple quantum well active layer, enabling efficient light extraction from the active area. Laterally-injected light-emitting diodes and laser diodes can enable brighter, more efficient devices that impact a wide range of wavelengths and applications. For UV wavelengths, applications include fluorescence-based biological sensing, epoxy curing, and water purification. For visible devices, applications include solid state lighting and projection systems.

Phosphorous Diffuser Diverged Blue Laser Diode for Indoor Lighting and Communication

KAUST Repository

Chi, Yu-Chieh; Hsieh, Dan-Hua; Lin, Chung-Yu; Chen, Hsiang-Yu; Huang, Chia-Yen; He, Jr-Hau; Ooi, Boon S.; DenBaars, Steven P.; Nakamura, Shuji; Kuo, Hao-Chung; Lin, Gong-Ru

2015-01-01

An advanced light-fidelity (Li-Fi) system based on the blue Gallium nitride (GaN) laser diode (LD) with a compact white-light phosphorous diffuser is demonstrated for fusing the indoor white-lighting and visible light communication (VLC

Singly-resonant sum frequency generation of visible light in a semiconductor disk laser

DEFF Research Database (Denmark)

Andersen, Martin Thalbitzer; Schlosser, P.J.; Hastie, J.E.

2009-01-01

In this paper a generic approach for visible light generation is presented. It is based on sum frequency generation between a semiconductor disk laser and a solid-state laser, where the frequency mixing is achieved within the cavity of the semiconductor disk laser using a singlepass of the solid......-state laser light. This exploits the good beam quality and high intra-cavity power present in the semiconductor disk laser to achieve high conversion efficiency. Combining sum frequency mixing and semiconductor disk lasers in this manner allows in principle for generation of any wavelength within the visible...

Characteristics of a Ti:sapphire laser pumped by a Nd:YAG laser and its analysis. Nd:YAG laser reiki Ti:sapphire laser no dosa tokusei to sono kaiseki

Energy Technology Data Exchange (ETDEWEB)

Okada, T.; Masumoto, J.; Mizunami, T.; Maeda, M.; Muraoka, K. (Kyushu Univ., Fukuoka (Japan). Faculty of Engineering)

1991-06-29

Although Ti: Sapphire expects of a possibility of being a light source much superior to a dye laser having been used as a wavelength variable laser for spectral analyses, it has a limitation that it does not oscillate directly in the visible and ultraviolet regions. In order to develop a light source that is synchronizable over ultraviolet-near infrared regions, by means of combining a Ti: Sapphire laser of a high peak power, comprising an oscillator and a multistage amplifier, with a non-linear frequency conversion method for harmonic generation and Raman conversion, a prototype Ti:Sapphire laser that is excited by YAG laser second harmonic, and that synchronizes with a prism was fabricated, and its operational characteristics were investigated. As a result, an output energy of 35.6 mJ at a maximum was obtained at a wavelength of 773 nm against an excitation energy of 129 mJ, a conversion efficiency of 38.2% was obtained against the absorption energy of the crystals, and a continuous synchronism was achieved over 750 to 900 nm. 4 refs., 9 figs., 1 tab.

Shaping laser accelerated ions for future applications – The LIGHT collaboration

International Nuclear Information System (INIS)

Busold, S.; Almomani, A.; Bagnoud, V.; Barth, W.; Bedacht, S.; Blažević, A.; Boine-Frankenheim, O.

2014-01-01

The generation of intense ion beams from high-intensity laser-generated plasmas has been the focus of research for the last decade. In the LIGHT collaboration the expertise of heavy ion accelerator scientists and laser and plasma physicists has been combined to investigate the prospect of merging these ion beams with conventional accelerator technology and exploring the possibilities of future applications. We report about the goals and first results of the LIGHT collaboration to generate, handle and transport laser driven ion beams. This effort constitutes an important step in research for next generation accelerator technologies

Shaping laser accelerated ions for future applications – The LIGHT collaboration

Energy Technology Data Exchange (ETDEWEB)

Busold, S., E-mail: s.busold@gsi.de [Institut für Kernphysik, Technische Universität Darmstadt, Schloßgartenstraße 9, D-64289 Darmstadt (Germany); Almomani, A. [Institut für angewandte Physik, Johann-Wolfgang-Goethe-Universität Frankfurt, Max von Laue Straße 1, D-60438 Frankfurt (Germany); Bagnoud, V. [GSI Helmholtzzentrum für Schwerionenforschung, Planckstraße 1, D-64291 Darmstadt (Germany); Helmholtz Institut Jena, Fröbelstieg 3, D-07734 Jena (Germany); Barth, W. [GSI Helmholtzzentrum für Schwerionenforschung, Planckstraße 1, D-64291 Darmstadt (Germany); Bedacht, S. [Institut für Kernphysik, Technische Universität Darmstadt, Schloßgartenstraße 9, D-64289 Darmstadt (Germany); Blažević, A. [GSI Helmholtzzentrum für Schwerionenforschung, Planckstraße 1, D-64291 Darmstadt (Germany); Helmholtz Institut Jena, Fröbelstieg 3, D-07734 Jena (Germany); Boine-Frankenheim, O. [GSI Helmholtzzentrum für Schwerionenforschung, Planckstraße 1, D-64291 Darmstadt (Germany); Institut für Theorie Elektromagnetischer Felder, Technische Universität Darmstadt, Schloßgartenstraße 8, D-64289 Darmstadt (Germany); and others

2014-03-11

The generation of intense ion beams from high-intensity laser-generated plasmas has been the focus of research for the last decade. In the LIGHT collaboration the expertise of heavy ion accelerator scientists and laser and plasma physicists has been combined to investigate the prospect of merging these ion beams with conventional accelerator technology and exploring the possibilities of future applications. We report about the goals and first results of the LIGHT collaboration to generate, handle and transport laser driven ion beams. This effort constitutes an important step in research for next generation accelerator technologies.

Lasers and intense pulsed light (IPL) association with cancerous lesions.

Science.gov (United States)

Ash, Caerwyn; Town, Godfrey; Whittall, Rebecca; Tooze, Louise; Phillips, Jaymie

2017-11-01

The development and use of light and lasers for medical and cosmetic procedures has increased exponentially over the past decade. This review article focuses on the incidence of reported cases of skin cancer post laser or IPL treatment. The existing evidence base of over 25 years of laser and IPL use to date has not raised any concerns regarding its long-term safety with only a few anecdotal cases of melanoma post treatment over two decades of use; therefore, there is no evidence to suggest that there is a credible cancer risk. Although laser and IPL technology has not been known to cause skin cancer, this does not mean that laser and IPL therapies are without long-term risks. Light therapies and lasers to treat existing lesions and CO 2 laser resurfacing can be a preventative measure against BCC and SCC tumour formation by removing photo-damaged keratinocytes and encouraged re-epithelisation from stem cells located deeper in the epidermis. A review of the relevant literature has been performed to address the issue of long-term IPL safety, focussing on DNA damage, oxidative stress induction and the impact of adverse events.

Ordering of pentacene in organic thin film transistors induced by irradiation of infrared light

International Nuclear Information System (INIS)

Wang, C. H.; Chen, S. W.; Hwang, J.

2009-01-01

The device performances of pentacene-based organic thin film transistors (OTFTs) were greatly improved by irradiation of infrared light. The field effect mobility and maximum drain current increase from 0.20±0.01 to 0.57±0.02 cm 2 /V s and 1.14x10 -5 to 4.91x10 -5 A, respectively. The (001) peak of the pentacene 'thin film' phase increases in intensity by 4.5 times after infrared irradiation at 50 W for 2 h. Two types of crystal orientations, i.e., 'crystal I' (2θ=5.91 deg.) and 'crystal II' (2θ=5.84 deg.), coexist in the pentacene. The improvement of the characteristics of OTFTs is attributed to crystallization and crystal reorientation induced by infrared light.

Studies on 16 μm spin-flip raman lasers in Tottori University

International Nuclear Information System (INIS)

Miyazaki, Kazuhiko

1986-01-01

This report outlines the studies on 16 μm spin-flip Raman lasers which have been carried out in Tottori University, Japan. Following the introductory section, the second section of the report deals with performance of infrared lasers for molecular laser isotope separation of UF 6 . It is stressed that the wavelength of the oscillation line should be accurately controlled in the vicinity of 628 cm -1 . The third section addresses 16 μm infrared lasers. Semiconductor diode lasers of Pb 1-x Sn x Te or Pb 1-x Sn x Se are available for the infrared region around 16 μm. Though the wavelength resolution is high and the oscillation wavelength is adjustable in these lasers, their oscillation outputs are not sufficient for the purpose of uranium separation. On the other hand, there are active studies on light-excited infrared gas lasers. It seems very difficult, however, to adjust the wavelength of their oscillation lines to the infrared absorption wavelength of 235 U. Thus, attention is currently focused on Raman lasers in the region around 16 μm. The fourth section briefly summarizes studies conducted in the University during these ten-odd years and the research facilities currently used. In particular, the major part is devoted to research and development of infrared NH 3 lasers and studies on InSb SFR (spin-flip Raman) lasers pumped with an NH 3 laser. A 12.97 μm and a 13.27 μm oscillation line have been obtained with a high output, which is hoped to serve for increasing the output of the 15.9 μm line of InSb SFR lasers. (Nogami, K.)

Growth and development of Arabidopsis thaliana under single-wavelength red and blue laser light

KAUST Repository

Ooi, Amanda Siok Lee

2016-09-23

Indoor horticulture offers a sensible solution for sustainable food production and is becoming increasingly widespread. However, it incurs high energy and cost due to the use of artificial lighting such as high-pressure sodium lamps, fluorescent light or increasingly, the light-emitting diodes (LEDs). The energy efficiency and light quality of currently available horticultural lighting is suboptimal, and therefore less than ideal for sustainable and cost-effective large-scale plant production. Here, we demonstrate the use of high-powered single-wavelength lasers for indoor horticulture. They are highly energy-efficient and can be remotely guided to the site of plant growth, thus reducing on-site heat accumulation. Furthermore, laser beams can be tailored to match the absorption profiles of different plant species. We have developed a prototype laser growth chamber and demonstrate that plants grown under laser illumination can complete a full growth cycle from seed to seed with phenotypes resembling those of plants grown under LEDs reported previously. Importantly, the plants have lower expression of proteins diagnostic for light and radiation stress. The phenotypical, biochemical and proteome data show that the single-wavelength laser light is suitable for plant growth and therefore, potentially able to unlock the advantages of this next generation lighting technology for highly energy-efficient horticulture.

Laser coupling to reduced-scale targets at Nif Early Light

Energy Technology Data Exchange (ETDEWEB)

Hinkel, D.E.; Schneider, M.B.; Young, B.K.; Holder, J.P.; Langdon, A.B.; Bonanno, G.; Bower, D.E.; Bruns, H.C.; Campbell, K.M.; Celeste, J.R.; Compton, S.; Costa, R.L.; Dewald, E.L.; Dixit, S.N.; Eckart, M.J.; Eder, D.C.; Edwards, M.J.; Ellis, A.D.; Emig, J.A.; Froula, D.H.; Glenzer, S.H.; Hargrove, D.; Haynam, C.A.; Heeter, R.F.; Henesian, M.A.; Holtmeier, G.; James, D.L.; Jancaitis, K.S.; Kalantar, K.H.; Kamperschroer, J.H.; Kauffman, R.L.; Kimbrough, J.; Kirkwood, R.K.; Koniges, A.E.; Landen, O.L.; Landon, M.; Lee, F.D.; MacGowan, B.J.; Mackinnon, A.J.; Manes, K.R.; Marshall, C.; May, M.J.; McDonald, J.W.; Menapace, J.; Moses, S.E.I.; Munro, D.H.; Murray, J.R.; Niemann, C.; Power, G.D.; Rekow, V.; Ruppe, J.A.; Schein, J.; Shepherd, R.; Singh, M.S.; Springer, P.T.; Still, C.H.; Suter, L.J.; Tietbohl, G.L.; Turner, R.E.; VanWonterghem, B.M.; Wallace, R.J.; Warrick, A.; Weber, F.; Wegner, P.J.; Williams, E.A.; Young, P.E. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Baldis, H.A. [California at Davis Univ., CA (United States); Pellinen, D.; Watts, P. [Bechtel Nevada Corporation, Livermore, CA (United States)

2006-06-15

Deposition of maximum laser energy into a small, high-Z enclosure in a short laser pulse creates a hot environment. Such targets were recently included in an experimental campaign using the first four of the 192 beams of the National Ignition Facility (NIF) under construction at the University of California Lawrence Livermore National Laboratory. These targets demonstrate good laser coupling, reaching a radiation temperature of 340 eV. In addition, the Raman backscatter spectrum contains features consistent with Brillouin backscatter of Raman forward scatter. Also, NIF Early Light diagnostics indicate that 20% of the direct backscatter from these reduced-scale targets is in the polarization orthogonal to that of the incident light. (authors)

Low power infrared laser modifies the morphology of lung affected with acute injury induced by sepsis

Science.gov (United States)

Sergio, L. P. S.; Trajano, L. A. S. N.; Thomé, A. M. C.; Mencalha, A. L.; Paoli, F.; Fonseca, A. S.

2018-06-01

Acute lung injury (ALI) is a potentially fatal disease characterized by uncontrolled hyperinflammatory responses in the lungs as a consequence of sepsis. ALI is divided into two sequential and time-dependent phases, exudative and fibroproliferative phases, with increased permeability of the alveolar barrier, causing edema and inflammation. However, there are no specific treatments for ALI. Low-power lasers have been successfully used in the resolution of acute inflammatory processes. The aim of this study was to evaluate the effects of low-power infrared laser exposure on alveolus and interalveolar septa of Wistar rats affected by ALI-induced by sepsis. Laser fluences, power, and the emission mode were those used in clinical protocols for the treatment of acute inflammation. Adult male Wistar rats were randomized into six groups: control, 10 J cm‑2, 20 J cm‑2, ALI, ALI  +  10 J cm‑2, and ALI  +  20 J cm‑2. ALI was induced by intraperitoneal Escherichia coli lipopolysaccharide (LPS). Lungs were removed and processed for hematoxylin–eosin staining. Morphological alterations induced by LPS in lung tissue were quantified by morphometry with a 32-point cyclic arcs test system in Stepanizer. Data showed that exposure to low-power infrared laser in both fluences reduced the thickening of interalveolar septa in lungs affected by ALI, increasing the alveolar space; however, inflammatory infiltrate was still observed. Our research showed that exposure to low-power infrared laser improves the lung parenchyma in Wistar rats affected by ALI, which could be an alternative approach for treatment of inflammatory lung injuries.

Mapping of electrophysiological response to transcranial infrared laser stimulation on the human brain in vivo measured by electroencephalography (Conference Presentation)

Science.gov (United States)

Wang, Xinlong; Reddy, Divya Dhandapani; Gonzalez-Lima, F.; Liu, Hanli

2017-02-01

Transcranial infrared laser stimulation (TILS) is a non-destructive and non-thermal photobiomodulation therapy or process on the human brain; TILS uses infrared light from lasers or LEDs and has gained increased recognition for its beneficial effects on a variety of neurological and psychological conditions. While the mechanism of TILS has been assumed to stem from cytochrome-c-oxidase (CCO), which is the last enzyme in the electron transportation chain and is the primary photoacceptor, no literature is found to report electrophysiological response to TILS. In this study, a 64-channel electroencephalography (EEG) system was employed to monitor electrophysiological activities from 15 healthy human participants before, during and after TILS. A placebo experimental protocol was also applied for rigorous comparison. After recording a 3-minute baseline, we applied a 1064-nm laser with a power of 3.5W on the right forehead of each human participant for 8 minutes, followed by a 5-minute recovery period. In 64-channel EEG data analysis, we utilized several methods (root mean square, principal component analysis followed by independent component analysis, permutation conditional mutual information, and time-frequency wavelet analysis) to reveal differences in electrophysiological response to TILS between the stimulated versus placebo group. The analyzed results were further investigated using general linear model and paired t-test to reveal statistically meaningful responses induced by TILS. Moreover, this study will provide spatial mapping of human electrophysiological and possibly neural network responses to TILS for first time, indicating the potential of EEG to be an effective method for monitoring neurological improvement induced by TILS.

Design of fiber optic probes for laser light scattering

Science.gov (United States)

Dhadwal, Harbans S.; Chu, Benjamin

1989-01-01

A quantitative analysis is presented of the role of optical fibers in laser light scattering. Design of a general fiber optic/microlens probe by means of ray tracing is described. Several different geometries employing an optical fiber of the type used in lightwave communications and a graded index microlens are considered. Experimental results using a nonimaging fiber optic detector probe show that due to geometrical limitations of single mode fibers, a probe using a multimode optical fiber has better performance, for both static and dynamic measurements of the scattered light intensity, compared with a probe using a single mode fiber. Fiber optic detector probes are shown to be more efficient at data collection when compared with conventional approaches to measurements of the scattered laser light. Integration of fiber optic detector probes into a fiber optic spectrometer offers considerable miniaturization of conventional light scattering spectrometers, which can be made arbitrarily small. In addition static and dynamic measurements of scattered light can be made within the scattering cell and consequently very close to the scattering center.

Infrared laser induced organic reactions. 2. Laser vs. thermal inducment of unimolecular and hydrogen bromide catalyzed bimolecular dehydration of alcohols

International Nuclear Information System (INIS)

Danen, W.C.

1979-01-01

It has been demonstrated that a mixture of reactant molecules can be induced by pulsed infrared laser radiation to react via a route which is totally different from the pathway resulting from heating the mixture at 300 0 C. The high-energy unimolecular elimination of H 2 O from ethanol in the presence of 2-propanol and HBr can be selectively induced with a pulsed CO 2 laser in preference to either a lower energy bimolecular HBr-catalyzed dehydration or the more facile dehydration of 2-propanol. Heating the mixture resulted in the almost exclusive reaction of 2-propanol to produce propylene. It was demonstrated that the bimolecular ethanol + HBr reaction cannot be effectively induced by the infrared laser radiation as evidenced by the detrimental effect on the yield of ethylene as the HBr pressure was increased. The selective, nonthermal inducement of H 2 O elimination from vibrationally excited ethanol in the presence of 2-propanol required relatively low reactant pressures. At higher pressures intermolecular V--V energy transfer allowed the thermally more facile dehydration from 2-propanol to become the predominant reaction channel

The effect of lunarlike satellites on the orbital infrared light curves of Earth-analog planets.

Science.gov (United States)

Moskovitz, Nicholas A; Gaidos, Eric; Williams, Darren M

2009-04-01

We have investigated the influence of lunarlike satellites on the infrared orbital light curves of Earth-analog extrasolar planets. Such light curves will be obtained by NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin missions as a consequence of repeat observations to confirm the companion status of a putative planet and determine its orbit. We used an energy balance model to calculate disk-averaged infrared (bolometric) fluxes from planet-satellite systems over a full orbital period (one year). The satellites are assumed to lack an atmosphere, have a low thermal inertia like that of the Moon, and span a range of plausible radii. The planets are assumed to have thermal and orbital properties that mimic those of Earth, while their obliquities and orbital longitudes of inferior conjunction remain free parameters. Even if the gross thermal properties of the planet can be independently constrained (e.g., via spectroscopy or visible-wavelength detection of specular glint from a surface ocean), only the largest (approximately Mars-sized) lunarlike satellites can be detected by light curve data from a TPF-like instrument (i.e., one that achieves a photometric signal-to-noise ratio of 10 to 20 at infrared wavelengths). Nondetection of a lunarlike satellite can obfuscate the interpretation of a given system's infrared light curve so that it may resemble a single planet with high obliquity, different orbital longitude of vernal equinox relative to inferior conjunction, and in some cases drastically different thermal characteristics. If the thermal properties of the planet are not independently established, then the presence of a lunarlike satellite cannot be inferred from infrared data, which would thus demonstrate that photometric light curves alone can only be used for preliminary study, and the addition of spectroscopic data will be necessary.

Review of infrared scene projector technology-1993

Science.gov (United States)

Driggers, Ronald G.; Barnard, Kenneth J.; Burroughs, E. E.; Deep, Raymond G.; Williams, Owen M.

1994-07-01

The importance of testing IR imagers and missile seekers with realistic IR scenes warrants a review of the current technologies used in dynamic infrared scene projection. These technologies include resistive arrays, deformable mirror arrays, mirror membrane devices, liquid crystal light valves, laser writers, laser diode arrays, and CRTs. Other methods include frustrated total internal reflection, thermoelectric devices, galvanic cells, Bly cells, and vanadium dioxide. A description of each technology is presented along with a discussion of their relative benefits and disadvantages. The current state of each methodology is also summarized. Finally, the methods are compared and contrasted in terms of their performance parameters.

Exotic behavior of molecules in intense laser light fields. New research directions

Energy Technology Data Exchange (ETDEWEB)

Yamanouchi, Kaoru [Tokyo Univ., Department of Chemistry, Tokyo (Japan)

2002-08-01

The recent investigation of the dynamical behavior of molecules and clusters in intense laser fields has afforded us invaluable opportunities to understand fundamentals of the interaction between molecular species and light fields as well as to manipulate molecules and their dynamical pathways by taking advantage of characteristics of coherent ultrashort laser light fields. In the present report, new directions of this rapidly growing interdisciplinary research fields called molecular science in intense laser fields are discussed by referring to our recent studies. (author)

LIGHT - from laser ion acceleration to future applications

Science.gov (United States)

Roth, Markus; Light Collaboration

2013-10-01

Creation of high intensity multi-MeV ion bunches by high power lasers became a reliable tool during the last 15 years. The laser plasma source provides for TV/m accelerating field gradients and initially sub-ps bunch lengths. However, the large envelope divergence and the continuous exponential energy spectrum are substential drawbacks for many possible applications. To face this problem, the LIGHT collaboration was founded (Laser Ion Generation, Handling and Transport). The collaboration consists of several university groups and research centers, namely TU Darmstadt, JWGU Frankfurt, HI Jena, HZDR Dresden and GSI Darmstadt. The central goal is building a test beamline for merging laser ion acceleration with conventional accelerator infrastructure at the GSI facility. In the latest experiments, low divergent proton bunches with a central energy of up to 10 MeV and containing >109 particles could be provided at up to 2.2 m behind the plasma source, using a pulsed solenoid. In a next step, a radiofrequency cavity will be added to the beamline for phase rotation of these bunches, giving access to sub-ns bunch lengths and reaching highest intensities. An overview of the LIGHT objectives and the recent experimental results will be given. This work was supported by HIC4FAIR.

Cooperative effect of ultraviolet and near-infrared beams in laser-induced condensation

Energy Technology Data Exchange (ETDEWEB)

Matthews, M.; Henin, S.; Pomel, F.; Kasparian, J.; Wolf, J.-P. [Université de Genève, GAP-Biophotonics, Chemin de Pinchat 22, 1211 Geneva 4 (Switzerland); Théberge, F.; Daigle, J.-F. [Defence R and D Canada Valcartier, 2459 de la Bravoure Blvd., Quebec (Qc) G3J 1X5 (Canada); Lassonde, P.; Kieffer, J.-C. [INRS-EMT, 1650 Lionel Boulet Blvd., Varennes, Quebec (Qc) J3X1S2 (Canada)

2013-12-23

We demonstrate the cooperative effect of near infrared (NIR) and ultraviolet (UV) beams on laser-induced condensation. Launching a UV laser after a NIR pulse yields up to a 5-fold increase in the production of nanoparticles (25–300 nm) as compared to a single NIR beam. This cooperative effect exceeds the sum of those from the individual beams and occurs for delays up to 1 μs. We attribute it to the UV photolysis of ozone created by the NIR pulses. The resulting OH radicals oxidize NO{sub 2} and volatile organic compounds, producing condensable species.

High-efficiency electroluminescence and amplified spontaneous emission from a thermally activated delayed fluorescent near-infrared emitter

Science.gov (United States)

Kim, Dae-Hyeon; D'Aléo, Anthony; Chen, Xian-Kai; Sandanayaka, Atula D. S.; Yao, Dandan; Zhao, Li; Komino, Takeshi; Zaborova, Elena; Canard, Gabriel; Tsuchiya, Youichi; Choi, Eunyoung; Wu, Jeong Weon; Fages, Frédéric; Brédas, Jean-Luc; Ribierre, Jean-Charles; Adachi, Chihaya

2018-02-01

Near-infrared organic light-emitting diodes and semiconductor lasers could benefit a variety of applications including night-vision displays, sensors and information-secured displays. Organic dyes can generate electroluminescence efficiently at visible wavelengths, but organic light-emitting diodes are still underperforming in the near-infrared region. Here, we report thermally activated delayed fluorescent organic light-emitting diodes that operate at near-infrared wavelengths with a maximum external quantum efficiency of nearly 10% using a boron difluoride curcuminoid derivative. As well as an effective upconversion from triplet to singlet excited states due to the non-adiabatic coupling effect, this donor-acceptor-donor compound also exhibits efficient amplified spontaneous emission. By controlling the polarity of the active medium, the maximum emission wavelength of the electroluminescence spectrum can be tuned from 700 to 780 nm. This study represents an important advance in near-infrared organic light-emitting diodes and the design of alternative molecular architectures for photonic applications based on thermally activated delayed fluorescence.

Fiber-delivered mid-infrared (6-7) laser ablation of retinal tissue under perfluorodecalin

Science.gov (United States)

Mackanos, Mark A.; Joos, Karen M.; Jansen, E. Duco

2003-07-01

The Er:YAG laser (l=2.94mm) is an effective tool in vitreo-retinal surgery. Pulsed mid-infrared (l=6.45 mm) radiation from the Free Electron Laser has been touted as a potentially superior cutting tool. To date, use of this laser has been limited to applications in an air environment. The goal of this study was: 1) determine feasibility of fiberoptic delivery of 6.45mm using silverhalide fibers (d=700mm); 2) use infrared transparent vitreous substitute (perfluorodecalin) to allow non-contact ablation of the retina at 6.45mm. Fiber damage threshold=7.8J/cm2 (0.54GW/cm2) while transmission loss=0.54dB/m, allowing supra-ablative radiant exposures to the target. FTIR measurements of perfluorodecalin at 6.45mm yielded ma=3mm-1. Pump-probe imaging of ablation of a tissue-phantom through perfluorodecalin showed feasibility of non-contact ablation at l=6.45mm. Ablation of the retinal membranes of enucleated pig eyes was carried out under perfluorodecalin (5 Hz, 1.3 J/cm2). Each eye was cut along its equator to expose the retina. Vitreous was replaced by perfluorodecalin and laser radiation was delivered to the retina via the silverhalide fiber. The eye was rotated (at 2 rpm) using a stepper motor (0.9o/step) to create an ablation circle around the central axis of the retina (50% spot-to-spot overlap). Histological analysis of ablation yield and collateral damage will be presented. We have shown that using l=6.45mm delivered via silver halide fibers through perfluorodecalin allowed non-contact laser ablation. Remote structures are shielded, as the radiant exposure falls below the ablation threshold owing non-negligible absorption of perfluorodecalin at 6.45mm. This may optimize efficacy and safety of laser-based vitreoretinal surgery.

Growth experiment in lettuce [Lactuca sativa] using laser light

International Nuclear Information System (INIS)

Mori, Y.; Takatsuji, M.

2001-01-01

Photosynthetic rate, relative growth rate and vitamin C contents were measured in lettuce cultivated under red and blue lasers and the results were compared with those cultivated under light emitting diodes (LED). It was found that lettuce grew fairly healthily under red laser diode (650 nm) and blue laser (442 nm) with R/B ratio 10. However, both photosynthetic rate and growth rate rather diminished compared with LED cases. As for vitamin C contents, the result was about the same as LED cases

Silicon light-emitting diodes and lasers photon breeding devices using dressed photons

CERN Document Server

Ohtsu, Motoichi

2016-01-01

This book focuses on a novel phenomenon named photon breeding. It is applied to realizing light-emitting diodes and lasers made of indirect-transition-type silicon bulk crystals in which the light-emission principle is based on dressed photons. After presenting physical pictures of dressed photons and dressed-photon phonons, the principle of light emission by using dressed-photon phonons is reviewed. A novel phenomenon named photon breeding is also reviewed. Next, the fabrication and operation of light emitting diodes and lasers are described The role of coherent phonons in these devices is discussed. Finally, light-emitting diodes using other relevant crystals are described and other relevant devices are also reviewed.

Laser safety in design of near-infrared scanning LIDARs

Science.gov (United States)

Zhu, X.; Elgin, D.

2015-05-01

3D LIDARs (Light Detection and Ranging) with 1.5μm nanosecond pulse lasers have been increasingly used in different applications. The main reason for their popularity is that these LIDARs have high performance while at the same time can be made eye-safe. Because the laser hazard effect on eyes or skin at this wavelength region (industrial mining applications. We have incorporated the laser safety requirements in the LIDAR design and conducted laser safety analysis for different operational scenarios. While 1.5μm is normally said to be the eye-safe wavelength, in reality a high performance 3D LIDAR needs high pulse energy, small beam size and high pulse repetition frequency (PRF) to achieve long range, high resolution and high density images. The resulting radiant exposure of its stationary beam could be many times higher than the limit for a Class 1 laser device. Without carefully choosing laser and scanning parameters, including field-of-view, scan speed and pattern, a scanning LIDAR can't be eye- or skin-safe based only on its wavelength. This paper discusses the laser safety considerations in the design of eye-safe scanning LIDARs, including laser pulse energy, PRF, beam size and scanning parameters in two basic designs of scanning mechanisms, i.e. galvanometer based scanner and Risley prism based scanner. The laser safety is discussed in terms of device classification, nominal ocular hazard distance (NOHD) and safety glasses optical density (OD).

Effect of high-frequency near-infrared diode laser irradiation on periodontal tissues during experimental tooth movement in rats.

Science.gov (United States)

Gunji, Hidemi; Kunimatsu, Ryo; Tsuka, Yuji; Yoshimi, Yuki; Sumi, Keisuke; Awada, Tetsuya; Nakajima, Kengo; Kimura, Aya; Hiraki, Tomoka; Hirose, Naoto; Yanoshita, Makoto; Tanimoto, Kotaro

2018-02-05

Tooth movement during orthodontic treatment is associated with bone neoplasticity and bone resorption on the tension and pressure sides. Previous clinical studies have suggested that low-power laser irradiation can accelerate tooth movement during orthodontic treatment, although the underlying mechanism remains unclear. In this study, we used a high-frequency near-infrared diode laser that generates less heat and examined the histologic changes in periodontal tissue during experimental tooth movement with laser irradiation. A nickel-titanium closed coil was mounted between the maxillary left side first molar and incisor of rats to model experimental tooth movement. The laser-irradiation and the control groups were set, and the amount of movement of the first molar on 7th and 14th days after the start of pulling of the first molar tooth on the maxillary left was measured by three-dimensional analysis of µCT. After tooth movement, tissue samples from the mesial and tension sides were collected, and successive horizontal sections were prepared and examined using hematoxylin-eosin and TRAP staining and immunohistochemical staining for RANKL, OPG, ALP, and proliferating cell nuclear antigen (PCNA). Changes in tissue temperature following laser irradiation were also examined. Laser irradiation significantly increased tooth movement compared with non-irradiated controls. Histologic staining of the pressure-side mesial root in laser-irradiated rats revealed enhanced RANKL expression and increased numbers of TRAP-positive cells compared with controls. By contrast, on the tension side, laser irradiation led to increased expression of ALP and PCNA. These data indicate that high-frequency near-infrared diode laser irradiation on the pressure side upregulates RANKL expression and accelerates osteoclast differentiation, facilitating bone resorption, whereas bone formation is induced on the tension side. This study demonstrates that high-frequency near-infrared diode laser

Nanoimprinted polymer chips for light induced local heating of liquids in micro- and nanochannels

DEFF Research Database (Denmark)

Thamdrup, Lasse Højlund; Pedersen, Jonas Nyvold; Flyvbjerg, Henrik

2010-01-01

A nanoimprinted polymer chip with a thin near-infrared absorber layer that enables light-induced local heating (LILH) of liquids inside micro- and nanochannels is presented. An infrared laser spot and corresponding hot-spot could be scanned across the device. Large temperature gradients yield...... a 785 nm laser diode was focused from the backside of the chip to a spot diameter down to 5 ..m in the absorber layer, yielding a localized heating (Gaussian profile) and large temperature gradients in the liquid in the nanochannels. A laser power of 38 mW yielded a temperature of 40°C in the center...

High speed FPGA-based Phasemeter for the far-infrared laser interferometers on EAST

Science.gov (United States)

Yao, Y.; Liu, H.; Zou, Z.; Li, W.; Lian, H.; Jie, Y.

2017-12-01

The far-infrared laser-based HCN interferometer and POlarimeter/INTerferometer\\break (POINT) system are important diagnostics for plasma density measurement on EAST tokamak. Both HCN and POINT provide high spatial and temporal resolution of electron density measurement and used for plasma density feedback control. The density is calculated by measuring the real-time phase difference between the reference beams and the probe beams. For long-pulse operations on EAST, the calculation of density has to meet the requirements of Real-Time and high precision. In this paper, a Phasemeter for far-infrared laser-based interferometers will be introduced. The FPGA-based Phasemeter leverages fast ADCs to obtain the three-frequency signals from VDI planar-diode Mixers, and realizes digital filters and an FFT algorithm in FPGA to provide real-time, high precision electron density output. Implementation of the Phasemeter will be helpful for the future plasma real-time feedback control in long-pulse discharge.

Near-infrared light-responsive dynamic wrinkle patterns.

Science.gov (United States)

Li, Fudong; Hou, Honghao; Yin, Jie; Jiang, Xuesong

2018-04-01

Dynamic micro/nanopatterns provide an effective approach for on-demand tuning of surface properties to realize a smart surface. We report a simple yet versatile strategy for the fabrication of near-infrared (NIR) light-responsive dynamic wrinkles by using a carbon nanotube (CNT)-containing poly(dimethylsiloxane) (PDMS) elastomer as the substrate for the bilayer systems, with various functional polymers serving as the top stiff layers. The high photon-to-thermal energy conversion of CNT leads to the NIR-controlled thermal expansion of the elastic CNT-PDMS substrate, resulting in dynamic regulation of the applied strain (ε) of the bilayer system by the NIR on/off cycle to obtain a reversible wrinkle pattern. The switchable surface topological structures can transfer between the wrinkled state and the wrinkle-free state within tens of seconds via NIR irradiation. As a proof-of-concept application, this type of NIR-driven dynamic wrinkle pattern was used in smart displays, dynamic gratings, and light control electronics.

Visible/IR light and x-rays in femtosecond synchronism from an x-ray free-electron laser

International Nuclear Information System (INIS)

Adams, B. A.; Experimental Facilities Division

2005-01-01

A way is proposed to obtain pulses of visible/infrared light in femtosecond synchronism with x-rays from an x-ray free-electron laser (XFEL), using the recently proposed emittance-slicing technique. In an XFEL undulator, only the short section of an electron bunch whose emittance is left unchanged by the slicing will emit intense coherent x-rays in the XFEL undulator. At the same time, the bunch emits highly collimated transition undulator radiation (TUR) into a cone whose opening angle is the reciprocal relativisticity parameter gamma. Due to the variation of the transverse momentum induced by the emittance slicing, the effective number of charges contributing to the TUR varies along the bunch, and is higher in the sliced-out part that emits the coherent x-rays. As with coherent synchrotron radiation (CSR), the TUR is thus coherently enhanced (CTUR) at near-infrared wavelengths. Coming from the same part of the bunch the CTUR and the coherent x-rays are perfectly synchronized to each other. Because both types of radiation are generated in the long straight XFEL undulator, there are no dispersion effects that might induce a timing jitter. With typical XFEL parameters, the energy content of the single optical cycle of near-IR CTUR light is about 100 Nano-Joule, which is quite sufficient for most pump-probe experiments

Fabrication of versatile cladding light strippers and fiber end-caps with CO2 laser radiation

Science.gov (United States)

Steinke, M.; Theeg, T.; Wysmolek, M.; Ottenhues, C.; Pulzer, T.; Neumann, J.; Kracht, D.

2018-02-01

We report on novel fabrication schemes of versatile cladding light strippers and end-caps via CO2 laser radiation. We integrated cladding light strippers in SMA-like connectors for reliable and stable fiber-coupling of high-power laser diodes. Moreover, the application of cladding light strippers in typical fiber geometries for high-power fiber lasers was evaluated. In addition, we also developed processes to fuse end-caps to fiber end faces via CO2 laser radiation and inscribe the fibers with cladding light strippers near the end-cap. Corresponding results indicate the great potential of such devices as a monolithic and low-cost alternative to SMA connectors.

III-nitride Photonic Integrated Circuit: Multi-section GaN Laser Diodes for Smart Lighting and Visible Light Communication

KAUST Repository

Shen, Chao

2017-01-01

The past decade witnessed the rapid development of III-nitride light-emitting diodes (LEDs) and laser diodes (LDs), for smart lighting, visible-light communication (VLC), optical storage, and internet-of-things. Recent studies suggested that the Ga

A color fusion method of infrared and low-light-level images based on visual perception

Science.gov (United States)

Han, Jing; Yan, Minmin; Zhang, Yi; Bai, Lianfa

2014-11-01

The color fusion images can be obtained through the fusion of infrared and low-light-level images, which will contain both the information of the two. The fusion images can help observers to understand the multichannel images comprehensively. However, simple fusion may lose the target information due to inconspicuous targets in long-distance infrared and low-light-level images; and if targets extraction is adopted blindly, the perception of the scene information will be affected seriously. To solve this problem, a new fusion method based on visual perception is proposed in this paper. The extraction of the visual targets ("what" information) and parallel processing mechanism are applied in traditional color fusion methods. The infrared and low-light-level color fusion images are achieved based on efficient typical targets learning. Experimental results show the effectiveness of the proposed method. The fusion images achieved by our algorithm can not only improve the detection rate of targets, but also get rich natural information of the scenes.

Time-resolved far-infrared experiments at the National Synchrotron Light Source. Final report

International Nuclear Information System (INIS)

Tanner, D.B.; Reitze, D.H.; Carr, G.L.

1999-01-01

A facility for time-resolved infrared and far-infrared spectroscopy has been built and commissioned at the National Synchrotron Light Source. This facility permits the study of time dependent phenomena over a frequency range from 2-8000cm -1 (0.25 meV-1 eV). Temporal resolution is approximately 200 psec and time dependent phenomena in the time range out to 100 nsec can be investigated

Laser-produced plasma-extreme ultraviolet light source for next generation lithography

International Nuclear Information System (INIS)

Nishihara, Katsunobu; Nishimura, Hiroaki; Gamada, Kouhei; Murakami, Masakatsu; Mochizuki, Takayasu; Sasaki, Akira; Sunahara, Atsushi

2005-01-01

Extreme ultraviolet (EUV) lithography is the most promising candidate for the next generation lithography for the 45 nm technology node and below. EUV light sources under consideration use 13.5 nm radiations from multicharged xenon, tin and lithium ions, because Mo/Si multiplayer mirrors have high reflectivity at this wavelength. A review of laser-produced plasma (LPP) EUV light sources is presented with a focus on theoretical and experimental studies under the auspices of the Leading Project promoted by MEXT. We discuss three theoretical topics: atomic processes in the LPP-EUV light source, conversion efficiency from laser light to EUV light at 13.5 nm wave-length with 2% bound width, and fast ion spectra. The properties of EUV emission from tin and xenon plasmas are also shown based on experimental results. (author)

Far infrared spectroscopy of high-Tc superconductors at the National Synchrotron Light Source

International Nuclear Information System (INIS)

Perkowitz, S.; Williams, G.P.

1989-01-01

This paper reports the first far infrared transmission spectra for micron-thick films of high-T c rare-earth superconductors such as DyBaCuO, with implications for the superconducting gap. Spectra were obtained at Brookhaven's National Synchrotron Light Source, a new high-intensity, broad-band millimeter to infrared source. The National Synchrotron Light Source at Brookhaven National Laboratory, known for powerful X-ray and UV output, is also a high-intensity (10 to 1000 times above a black body), high-brightness (intensity per solid angle), broad-band, picosecond, millimeter to infrared source. These features make it valuable for far-infrared condensed matter experiments, especially those in highly absorbing or extremely small systems. A first application has been to measure very small infrared transmissions through thick bulk-like high-T c superconducting films. Preliminary measurements through films of the conventional superconductor Nb 3 Ge established techniques. These were followed by the first measurements (to the author's knowledge) through micron-thick films of high-T c rare-earth superconductors such as DyBaCuO over 10-300 cm -1 , which includes the superconducting gap according to BCS or moderately strong-coupled theory. The authors discuss the transmission evidence bearing on the existence of a gap and other important features of high-T c superconductors, and describe the synchrotron and instrumentation features which make possible these unusual measurements

Laser-based irradiation apparatus and method to measure the functional dose-rate response of semiconductor devices

Science.gov (United States)

Horn, Kevin M [Albuquerque, NM

2008-05-20

A broad-beam laser irradiation apparatus can measure the parametric or functional response of a semiconductor device to exposure to dose-rate equivalent infrared laser light. Comparisons of dose-rate response from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems can determine if aging has affected the device's overall functionality. The dependence of these changes on equivalent dose-rate pulse intensity and/or duration can be measured with the apparatus. The synchronized introduction of external electrical transients into the device under test can be used to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure while exposing the device to dose-rate equivalent infrared laser light.

Infrared scanning laser ophthalmoscope imaging of the macula and its correlation with functional loss and structural changes in patients with stargardt disease.

Science.gov (United States)

Anastasakis, Anastasios; Fishman, Gerald A; Lindeman, Martin; Genead, Mohamed A; Zhou, Wensheng

2011-05-01

To correlate the degree of functional loss with structural changes in patients with Stargardt disease. Eighteen eyes of 10 patients with Stargardt disease were studied. Scanning laser ophthalmoscope infrared images were compared with corresponding spectral-domain optical coherence tomography scans. Additionally, scanning laser ophthalmoscope microperimetry was performed, and results were superimposed on scanning laser ophthalmoscope infrared images and in selected cases on fundus autofluorescence images. Seventeen of 18 eyes showed a distinct hyporeflective foveal and/or perifoveal area with distinct borders on scanning laser ophthalmoscope infrared images, which was less evident on funduscopy and incompletely depicted in fundus autofluorescence images. This hyporeflective zone corresponded to areas of significantly elevated psychophysical thresholds on microperimetry testing, in addition to thinning of the retinal pigment epithelium and disorganization or loss of the photoreceptor cell inner segment-outer segment junction and external-limiting membrane on spectral-domain optical coherence tomography. Scanning laser ophthalmoscope infrared fundus images are useful for depicting retinal structural changes in patients with Stargardt disease. A spectral-domain optical coherence tomography/scanning laser ophthalmoscope microperimetry device allows for a direct correlation of structural abnormalities with functional defects that will likely be applicable for the determination of retinal areas for potential improvement of retinal function in these patients during future clinical trials and for the monitoring of the diseases' natural history.

Black phosphorus saturable absorber for a diode-pumped passively Q-switched Er:CaF2 mid-infrared laser

Science.gov (United States)

Li, Chun; Liu, Jie; Guo, Zhinan; Zhang, Han; Ma, Weiwei; Wang, Jingya; Xu, Xiaodong; Su, Liangbi

2018-01-01

A multilayer black phosphorus, as a novel two dimensional saturable absorber, has superb saturable absorption properties for a Er:CaF2 solid-state pulse laser. The pulse laser is realized at mid-infrared region with the passively Q-switched technology by a diode-pumping. The high-quality black phosphorus saturable absorber is fabricated by liquid phase exfoliation method. The pulse laser generates the pulses operation with the pulse duration of 954.8 ns, the repetition rate of 41.93 kHz, the pulse energy of 4.25 μJ and the peak power of 4.45 W. Our work demonstrates that black phosphorus could be used as a kind of efficient mid-infrared region optical absorber for ultrafast photonics.

Hollow core waveguide as mid-infrared laser modal beam filter

Energy Technology Data Exchange (ETDEWEB)

Patimisco, P.; Giglio, M.; Spagnolo, V. [Dipartimento Interateneo di Fisica, Università e Politecnico di Bari, CNR-IFN UOS BARI, Via Amendola 173, 70126 Bari (Italy); Sampaolo, A. [Dipartimento Interateneo di Fisica, Università e Politecnico di Bari, CNR-IFN UOS BARI, Via Amendola 173, 70126 Bari (Italy); Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States); Kriesel, J. M. [Opto-Knowledge Systems, Inc. (OKSI), 19805 Hamilton Ave., Torrance, California 90502-1341 (United States); Tittel, F. K. [Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States)

2015-09-21

A novel method for mid-IR laser beam mode cleaning employing hollow core waveguide as a modal filter element is reported. The influence of the input laser beam quality on fiber optical losses and output beam profile using a hollow core waveguide with 200 μm-bore size was investigated. Our results demonstrate that even when using a laser with a poor spatial profile, there will exist a minimum fiber length that allows transmission of only the Gaussian-like fundamental waveguide mode from the fiber, filtering out all the higher order modes. This essentially single mode output is preserved also when the waveguide is bent to a radius of curvature of 7.5 cm, which demonstrates that laser mode filtering can be realized even if a curved light path is required.

Near-Infrared Confocal Laser Reflectance Cytoarchitectural Imaging of the Substantia Nigra and Cerebellum in the Fresh Human Cadaver.

Science.gov (United States)

Cheyuo, Cletus; Grand, Walter; Balos, Lucia L

2017-01-01

Cytoarchitectural neuroimaging remains critical for diagnosis of many brain diseases. Fluorescent dye-enhanced, near-infrared confocal in situ cellular imaging of the brain has been reported. However, impermeability of the blood-brain barrier to most fluorescent dyes limits clinical utility of this modality. The differential degree of reflectance from brain tissue with unenhanced near-infrared imaging may represent an alternative technique for in situ cytoarchitectural neuroimaging. We assessed the utility of unenhanced near-infrared confocal laser reflectance imaging of the cytoarchitecture of the cerebellum and substantia nigra in 2 fresh human cadaver brains using a confocal near-infrared laser probe. Cellular images based on near-infrared differential reflectance were captured at depths of 20-180 μm from the brain surface. Parts of the cerebellum and substantia nigra imaged using the probe were subsequently excised and stained with hematoxylin and eosin for histologic correlation. Near-infrared reflectance imaging revealed the 3-layered cytoarchitecture of the cerebellum, with Purkinje cells appearing hyperreflectant. In the substantia nigra, neurons appeared hyporeflectant with hyperreflectant neuromelanin cytoplasmic inclusions. Cytoarchitecture of the cerebellum and substantia nigra revealed on near-infrared imaging closely correlated with the histology on hematoxylin-eosin staining. We showed that unenhanced near-infrared reflectance imaging of fresh human cadaver brain can reliably identify and distinguish neurons and detailed cytoarchitecture of the cerebellum and substantia nigra. Copyright © 2016 Elsevier Inc. All rights reserved.

Enhanced light scattering in Si nanostructures produced by pulsed laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Sberna, P. M.; Scapellato, G. G.; Boninelli, S.; Miritello, M.; Crupi, I.; Bruno, E.; Privitera, V.; Simone, F.; Mirabella, S. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofia 64, 95123 Catania (Italy); Piluso, N. [IMM-CNR, VIII strada 5, 95121 Catania (Italy)

2013-11-25

An innovative method for Si nanostructures (NS) fabrication is proposed, through nanosecond laser irradiation (λ = 532 nm) of thin Si film (120 nm) on quartz. Varying the laser energy fluences (425–1130 mJ/cm{sup 2}) distinct morphologies of Si NS appear, going from interconnected structures to isolated clusters. Film breaking occurs through a laser-induced dewetting process. Raman scattering is enhanced in all the obtained Si NS, with the largest enhancement in interconnected Si structures, pointing out an increased trapping of light due to multiple scattering. The reported method is fast, scalable and cheap, and can be applied for light management in photovoltaics.

Visible Discrimination of Broadband Infrared Light by Dye-Enhanced Upconversion in Lanthanide-Doped Nanocrystals

Directory of Open Access Journals (Sweden)

Charles G. Dupuy

2014-01-01

Full Text Available Optical upconversion of near infrared light to visible light is an attractive way to capture the optical energy or optical information contained in low-energy photons that is otherwise lost to the human eye or to certain photodetectors and solar cells. Until the recent application of broadband absorbing optical antennas, upconversion efficiency in lanthanide-doped nanocrystals was limited by the weak, narrow atomic absorption of a handful of sensitizer elements. In this work, we extend the role of the optical antenna to provide false-color, visible discrimination between bands of infrared radiation. By pairing different optical antenna dyes to specific nanoparticle compositions, unique visible emission is associated with different bands of infrared excitation. In one material set, the peak emission was increased 10-fold, and the width of the spectral response was increased more than 10-fold.

Coherent laser phase retrieval in the presence of measurement imperfections and incoherent light

DEFF Research Database (Denmark)

Hansen, Anders Kragh

2017-01-01

-plane Gerchberg–Saxton algorithm and demonstrate that it is highly successful at extracting the intensity profile and wavefront of the spatially coherent part of the light from various lasers, including tapered laser diodes, at a very high fidelity despite the presence of incoherent light and noise....

Requirements and design of a high stable infrared free electron laser at LBL

International Nuclear Information System (INIS)

Kim, K.J.; Berz, M.; Chattopadhyay, S.; Gough, R.; Kim, C.; Kung, A.H.; Xie, M.; Edighoffer, J.; Stein, W.

1990-06-01

An infrared free electron laser (IRFEL) is being designed for the Chemical Dynamics Research Laboratory (CDRL) at LBL. The FEL is based on a 50 MeV RF linac operating in synchronization to the Advanced Light Source (ALS), and will produce intense (100 μJ per micropulse), narrow bandwidth (narrower than 0.1%) radiation between 3 μ and 50 μ. In the design, we pay particular attention to the FEL stability issues and require that the fluctuations in electron beam energy and in timing be less than 0.05% and 0.1 ps, respectively. The FEL spectrum can then be stabilized to about 10 -3 , or if grating is used, to 10 -4 . We discuss various sources of fluctuations in the gun, the bunchers and the accelerator sections, as well as the feedback and feedforward schemes to reduce these fluctuations. The accelerator structure is chosen to be of the side coupled, standing wave type for easier control. The beam transport is made isochronous to avoid the coupling between the energy and the timing fluctuations. 9 refs., 2 figs

Indirect absorption spectroscopy using quantum cascade lasers: mid-infrared refractometry and photothermal spectroscopy.

Science.gov (United States)

Pfeifer, Marcel; Ruf, Alexander; Fischer, Peer

2013-11-04

We record vibrational spectra with two indirect schemes that depend on the real part of the index of refraction: mid-infrared refractometry and photothermal spectroscopy. In the former, a quantum cascade laser (QCL) spot is imaged to determine the angles of total internal reflection, which yields the absorption line via a beam profile analysis. In the photothermal measurements, a tunable QCL excites vibrational resonances of a molecular monolayer, which heats the surrounding medium and changes its refractive index. This is observed with a probe laser in the visible. Sub-monolayer sensitivities are demonstrated.

Effects of polychromatic visible and infrared light on biological liquid media.

Science.gov (United States)

Zilov, V G; Khadartsev, A A; Bitsoev, V D

2014-08-01

Experimental study of the effects of polychromatic visible and infrared light on biological fluids was carried out in order to validate the new approaches to phototherapy. Polychromatic light generated by Bioptron device at different modes and frequencies was released through the fiberoptic cable, including the exposure paralleled by CO2 saturation of water and exposure from a device placed 10 cm above the water surface, which ensured maximum light absorption. The effects of irradiation were recorded in 26 and 15 min, while the increase of light absorption by blood plasma in vivo was recorded 1 h after a bath with water pre-exposed to polarized light. Absorption bands corresponding to those for immunomodulatory, anti-inflammatory, and antiviral drugs, were detected. Changes in the spectra of valency oscillations, depending on the oscillation anharmonism values, were detected.

Quantum Cascade Laser-Based Infrared Microscopy for Label-Free and Automated Cancer Classification in Tissue Sections.

Science.gov (United States)

Kuepper, Claus; Kallenbach-Thieltges, Angela; Juette, Hendrik; Tannapfel, Andrea; Großerueschkamp, Frederik; Gerwert, Klaus

2018-05-16

A feasibility study using a quantum cascade laser-based infrared microscope for the rapid and label-free classification of colorectal cancer tissues is presented. Infrared imaging is a reliable, robust, automated, and operator-independent tissue classification method that has been used for differential classification of tissue thin sections identifying tumorous regions. However, long acquisition time by the so far used FT-IR-based microscopes hampered the clinical translation of this technique. Here, the used quantum cascade laser-based microscope provides now infrared images for precise tissue classification within few minutes. We analyzed 110 patients with UICC-Stage II and III colorectal cancer, showing 96% sensitivity and 100% specificity of this label-free method as compared to histopathology, the gold standard in routine clinical diagnostics. The main hurdle for the clinical translation of IR-Imaging is overcome now by the short acquisition time for high quality diagnostic images, which is in the same time range as frozen sections by pathologists.

Alopecia: a review of laser and light therapies.

Science.gov (United States)

Rangwala, Sophia; Rashid, Rashid M

2012-02-15

Since the 1980s, laser technology has become increasingly popular to treat a variety of cutaneous conditions. Its successful use as an epilator comes with the rare but interesting side effect of paradoxical hypertrichosis. In this review, we summarize cases describing hair growth after photoepilation, as well as studies testing laser and light sources as treatment for alopecia, particularly androgenetic alopecia and alopecia areata. We also discuss the possible biologic mechanisms by which phototherapy induces hair regeneration.

Anti-Neuroblastoma Activity of Gold Nanorods Bound with GD2 Monoclonal Antibody under Near-Infrared Laser Irradiation

International Nuclear Information System (INIS)

Peng, Ching-An; Wang, Chung-Hao

2011-01-01

High-risk neuroblastoma is one of the most common deaths in pediatric oncology. Current treatment of this disease involves a coordinated sequence of chemotherapy, surgery, and radiation. Further advances in therapy will require the targeting of tumor cells in a more selective and efficient way so that survival can be improved without substantially increasing toxicity. To achieve tumor-selective delivery, disialoganglioside (GD2) expressed by almost all neuroblastoma tumors represents a potential molecular target that can be exploited for tumor-selective delivery. In this study, GD2 monoclonal antibody (anti-GD2) was conjugated to gold nanorods (GNRs) which are one of anisotropic nanomaterials that can absorb near-infrared (NIR) laser light and convert it to energy for photothermolysis of tumor cells. Thiolated chitosan, due to its biocompatibility, was used to replace cetyltrimethylammonium bromide (CTAB) originally used in the synthesis of gold nanorods. In order to specifically target GD2 overexpressed on the surface of neuroblastoma stNB-V1 cells, anti-GD2 was conjugated to chitosan modified GNRs (CGNRs). To examine the fate of CGNRs conjugated with anti-GD2 after incubation with neuroblastoma cells, rhadoamine B was labeled on CGNRs functionalized with anti-GD2. Our results illustrated that anti-GD2-conjugated CGNRs were extensively endocytosed by GD2 + stNB-V1 neuroblastoma cells via antibody-mediated endocytosis. In addition, we showed that anti-GD2 bound CGNRs were not internalized by GD2 − SH-SY5Y neuroblastoma cells. After anti-GD2-linked CGNRs were incubated with neuroblatoma cells for six hours, the treated cells were further irradiated with 808 nm NIR laser. Post-NIR laser exposure, when examined by calcein-AM dye, stNB-V1 cells all underwent necrosis, while non-GD2 expressing SH-SY5Y cells all remained viable. Based on the in vitro study, CGNRs bound with anti-GD2 has the potential to be utilized as a therapeutic thermal coupling agent that generates

On stimulated scattering of laser light in inertial fusion energy targets

International Nuclear Information System (INIS)

Nikolic, Lj; Skoric, M.M.; Ishiguro, S.; Sato, T.

2002-11-01

Propagation of a laser light through regions of an underdense plasma is an active research topic in laser fusion. In particular, a large effort has been invested in studies of stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) which can reflect laser energy and produce energetic particles to preheat a fusion energy target. Experiments, theory and simulations agree on a complex interplay between various laser-plasma instabilities. By particle-in-cell simulations of an underdense electron-plasma, we have found, apart from the standard SRS, a strong backscattering near the electron plasma frequency at densities beyond the quarter critical. This novel instability, recognized in recent experiments as stimulated laser scattering on a trapped electron-acoustic mode (SEAS), is absent from a classical theory of laser-parametric instabilities. A parametric excitation of SEAS instability, is explained by a three-wave resonant decay of the incident laser light into a standing backscattered wave and a slow trapped electron acoustic wave (ω p ). Large SEAS pulsations, eventually suppressed by relativistic heating of electrons, are observed in our simulations. This phenomenon seems relevant to future hohlraum target and fast ignition experiments. (author)

Broadband pulsed difference frequency generation laser source centered 3326 nm based on ring fiber lasers

Science.gov (United States)

Chen, Guangwei; Li, Wenlei

2018-03-01

A broadband pulsed mid-infrared difference frequency generation (DFG) laser source based on MgO-doped congruent LiNbO3 bulk is experimentally demonstrated, which employs a homemade pulsed ytterbium-doped ring fiber laser and a continuous wave erbium-doped ring fiber laser to act as seed sources. The experimental results indicate that the perfect phase match crystal temperature is about 74.5∘C. The maximum spectrum bandwidth of idler is about 60 nm with suitable polarization states of fundamental lights. The central wavelength of idlers varies from 3293 nm to 3333 nm over the crystal temperature ranges of 70.4-76∘C. A jump of central wavelength exists around crystal temperature of 72∘C with variation of about 30 nm. The conversion efficiency of DFG can be tuned with the crystal temperature and polarization states of fundamental lights.

The efficiency of photovoltaic cells exposed to pulsed laser light

Science.gov (United States)

Lowe, R. A.; Landis, G. A.; Jenkins, P.

1993-01-01

Future space missions may use laser power beaming systems with a free electron laser (FEL) to transmit light to a photovoltaic array receiver. To investigate the efficiency of solar cells with pulsed laser light, several types of GaAs, Si, CuInSe2, and GaSb cells were tested with the simulated pulse format of the induction and radio frequency (RF) FEL. The induction pulse format was simulated with an 800-watt average power copper vapor laser and the RF format with a frequency-doubled mode-locked Nd:YAG laser. Averaged current vs bias voltage measurements for each cell were taken at various optical power levels and the efficiency measured at the maximum power point. Experimental results show that the conversion efficiency for the cells tested is highly dependent on cell minority carrier lifetime, the width and frequency of the pulses, load impedance, and the average incident power. Three main effects were found to decrease the efficiency of solar cells exposed to simulated FEL illumination: cell series resistance, LC 'ringing', and output inductance. Improvements in efficiency were achieved by modifying the frequency response of the cell to match the spectral energy content of the laser pulse with external passive components.

Through-transmission laser welding of glass fibre composite: Experimental light scattering identification

Science.gov (United States)

Cosson, Benoit; Asséko, André Chateau Akué; Dauphin, Myriam

2018-05-01

The purpose of this paper is to develop a cost-effective, efficient and quick to implement experimental optical method in order to predict the optical properties (extinction coefficient) of semi-transparent polymer composites. The extinction coefficient takes into account the effects due to the absorption and the scattering phenomena in a semi-transparent component during the laser processes, i.e. TTLW (through-transmission laser welding). The present method used a laser as light source and a reflex camera equipped with a macro lens as a measurement device and is based on the light transmission measurement through different thickness samples. The interaction between the incident laser beam and the semi-transparent composite is exanimated. The results are presented for the case of a semi-transparent composite reinforced with the unidirectional glass fiber (UD). A numerical method, ray tracing, is used to validate the experimental results. The ray tracing method is appropriate to characterize the light-scattering phenomenon in semi-transparent materials.

A review on laser and light-based therapies for alopecia areata.

Science.gov (United States)

Mlacker, Stephanie; Aldahan, Adam Souhail; Simmons, Brian James; Shah, Vidhi; McNamara, Colin Andrew; Samarkandy, Sahal; Nouri, Keyvan

2017-04-01

Alopecia areata is a form of non-scarring alopecia that results from a hyperactive immune response of T cells against hair follicles. Many patients with visible hair loss experience psychological and emotional distress, as a result of their cosmetic disfigurement, and frequently seek treatment. However, existing treatment methods, such as corticosteroids, topical irritants, sensitizing agents, immunosuppressants, and psoralen plus ultraviolet light A, may result in various adverse effects and often lack efficacy. Laser and light treatments offer a safe and effective alternative. This review aims to provide clinicians with a comprehensive summary of laser and light-based modalities used for the treatment of alopecia areata. Currently, the excimer laser is the most widely studied device and has shown positive results thus far. However, the development of future randomized controlled clinical trials will help determine the appropriate treatment protocols necessary, in order to achieve superior clinical outcomes.

Combining infrared- and green-laser stimulation sources in single-grain luminescence measurements of feldspar and quartz

DEFF Research Database (Denmark)

Duller, G.A.T.; Bøtter-Jensen, L.; Murray, A.S.

2003-01-01

A system designed for measurement of the optically stimulated luminescence (OSL) from individual sand-sized mineral grains has been constructed. Previously, this system was equipped only with a green laser emitting at 532 run, but now an infrared (IR) laser at 830 run has been added. It is now...... possible to interchangeably use the two laser sources for optical stimulation. This is especially valuable for the measurement of feldspars. The power density using the IR laser at the grain is similar to500 W cm(-2), and stimulation for 1 s reduces the OSL signal to near background level. Initial results...

Opto-injection into single living cells by femtosecond near-infrared laser

Science.gov (United States)

Peng, Cheng

This dissertation presents a novel technique to deliver membrane impermeable molecules into single living cells with the assistance of femtosecond (fs) near-infrared (NIR) laser pulses. This approach merges ultrafast laser technology with key biological, biomedical, and medical applications, such as gene transfection, gene therapy and drug delivery. This technique promises several major advantages, namely, very high transfection efficiency, high cell survival rate (≈100%) and fully preserved cell viabilities. It is also a promising method to deliver molecules into cells that are difficult or even completely resistant to established physical methods, such as microinjection by glass pipettes, electroporation, and biolistics. In this work, the system for fs NIR opto-injection was designed and built. Successful fs NIR opto-injection has been performed on several cell systems including single mammalian cells (bovine aortic endothelial cells), marine animal eggs (Spisula solidissima oocytes), and human cancer cells (fibrosarcoma HT1080) cultured in a tissue-like environment. The connections between laser parameters and cell responses were explored through further experiments and in-depth analyses, especially the relationship between dye uptake rate and incident laser intensity, and the relationship between pore size created on cell membranes and incident laser intensity. Dye uptake rate of the target cells was observed to depend on incident laser intensity. Pore size was found dependent on incident laser intensity. The conclusion was made that laser-induced breakdown and plasma-induced ablation in cell membrane are the physical principles that govern the process of fs NIR opto-injection.

High-order harmonics measured by the photon statistics of the infrared driving-field exiting the atomic medium.

Science.gov (United States)

Tsatrafyllis, N; Kominis, I K; Gonoskov, I A; Tzallas, P

2017-04-27

High-order harmonics in the extreme-ultraviolet spectral range, resulting from the strong-field laser-atom interaction, have been used in a broad range of fascinating applications in all states of matter. In the majority of these studies the harmonic generation process is described using semi-classical theories which treat the electromagnetic field of the driving laser pulse classically without taking into account its quantum nature. In addition, for the measurement of the generated harmonics, all the experiments require diagnostics in the extreme-ultraviolet spectral region. Here by treating the driving laser field quantum mechanically we reveal the quantum-optical nature of the high-order harmonic generation process by measuring the photon number distribution of the infrared light exiting the harmonic generation medium. It is found that the high-order harmonics are imprinted in the photon number distribution of the infrared light and can be recorded without the need of a spectrometer in the extreme-ultraviolet.

Laser light scatter experiments on plasma focus plant

International Nuclear Information System (INIS)

Wenzel, N.

1985-01-01

The plasma focus plant is an experiment on nuclear fusion, which is distinguished by a high neutron yield. Constituting an important method of diagnosis in plasma focussing, the laser light scatter method makes it possible, apart from finding the electron temperature and density, to determine the ion temperature resolved according to time and place and further, to study the occurrence of micro-turbulent effects. Starting from the theoretical basis, this dissertation describes light scatter measurements with ruby lasers on the POSEIDON plasma focus. They are given, together with earlier measurements on the Frascati 1 MJ plant and the Heidelberg 12 KJ plant. The development of the plasma parameters and the occurrence of superthermal light scatter events are discussed in connection with the dynamics of the plasma and the neutron emission characteristics of the individual plants. The results support the view that the thermo-nuclear neutron production at the plasma focus is negligible. Although the importance of micro-turbulent mechanisms in producing neutrons cannot be finally judged, important guidelines are given for the spatial and time relationships with plasma dynamics, plasma parameters and neutron emission. The work concludes with a comparison of all light scatter measurements at the plasma focus described in the literature. (orig.) [de

Mechanical properties and polymerization shrinkage of composite resins light-cured using two different lasers.

Science.gov (United States)

Kim, Tae-Wan; Lee, Jang-Hoon; Jeong, Seung-Hwa; Ko, Ching-Chang; Kim, Hyung-Il; Kwon, Yong Hoon

2015-04-01

The purpose of the present study was to investigate the usefulness of 457 and 473 nm lasers for the curing of composite resins during the restoration of damaged tooth cavity. Monochromaticity and coherence are attractive features of laser compared with most other light sources. Better polymerization of composite resins can be expected. Eight composite resins were light cured using these two lasers and a light-emitting diode (LED) light-curing unit (LCU). To evaluate the degrees of polymerization achieved, polymerization shrinkage and flexural and compressive properties were measured and compared. Polymerization shrinkage values by 457 and 473 nm laser, and LED ranged from 10.9 to 26.8, from 13.2 to 26.1, and from 11.5 to 26.3 μm, respectively. The values by 457 nm laser was significantly different from those by 473 and LED LCU (p0.05). For the tested LCUs, no specific LCU could consistently achieve highest strength and modulus from the specimens tested. Two lasers (457 and 473 nm) can polymerize composite resins to the level that LED LCU can achieve despite inconsistent trends of polymerization shrinkage and flexural and compressive properties of the tested specimens.

Near-infrared light activation of quenched liposomal Ce6 for synergistic cancer phototherapy with effective skin protection.

Science.gov (United States)

Feng, Liangzhu; Tao, Danlei; Dong, Ziliang; Chen, Qian; Chao, Yu; Liu, Zhuang; Chen, Meiwan

2017-05-01

Current photodynamic therapy (PDT) is suffering from limited efficacy towards hypoxia tumors and severe post-treatment photo-toxicity such as light-induced skin damages. To make PDT more effective in cancer treatment while being patient-comfortable, herein, a hexylamine conjugated chlorin e6 (hCe6) as the photosensitizer together with a lipophilic near-infrared (NIR) dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR) are co-encapsulated into polyethylene glycol (PEG) shelled liposomes. In the obtained DiR-hCe6-liposome, the photosensitizing effect of hCe6 is quenched by DiR via fluorescence resonance energy transfer (FRET). Interestingly, upon irradiation with a 785-nm NIR laser to photobleach DiR, both fluorescence and photodynamic effect of hCe6 in DiR-hCe6-liposome would be activated. Meanwhile, such NIR irradiation applied on tumors of mice with intravenous injection of DiR-hCe6-liposome could result in mild photothermal heating, which in turn would promote intra-tumor blood flow and relieve tumor hypoxia, contributing to the enhanced photodynamic tumor treatment. Importantly, compared to hCe6-loaded liposomes, DiR-hCe6-liposome without being activated by the 785-nm laser shows much lower skin photo-toxicity, demonstrating its great skin protection effect. This work demonstrates a promising yet simple strategy to prepare NIR-light-activatable photodynamic theranostics for synergistic cancer phototherapy, which is featured high specificity/efficacy in tumor treatment with minimal photo-toxicity towards the skin. Copyright © 2016. Published by Elsevier Ltd.

Porcine skin visible lesion thresholds for near-infrared lasers including modeling at two pulse durations and spot sizes.

Science.gov (United States)

Cain, C P; Polhamus, G D; Roach, W P; Stolarski, D J; Schuster, K J; Stockton, K L; Rockwell, B A; Chen, Bo; Welch, A J

2006-01-01

With the advent of such systems as the airborne laser and advanced tactical laser, high-energy lasers that use 1315-nm wavelengths in the near-infrared band will soon present a new laser safety challenge to armed forces and civilian populations. Experiments in nonhuman primates using this wavelength have demonstrated a range of ocular injuries, including corneal, lenticular, and retinal lesions as a function of pulse duration. American National Standards Institute (ANSI) laser safety standards have traditionally been based on experimental data, and there is scant data for this wavelength. We are reporting minimum visible lesion (MVL) threshold measurements using a porcine skin model for two different pulse durations and spot sizes for this wavelength. We also compare our measurements to results from our model based on the heat transfer equation and rate process equation, together with actual temperature measurements on the skin surface using a high-speed infrared camera. Our MVL-ED50 thresholds for long pulses (350 micros) at 24-h postexposure are measured to be 99 and 83 J cm(-2) for spot sizes of 0.7 and 1.3 mm diam, respectively. Q-switched laser pulses of 50 ns have a lower threshold of 11 J cm(-2) for a 5-mm-diam top-hat laser pulse.

Can thermal lasers promote skin wound healing?

Science.gov (United States)

Capon, Alexandre; Mordon, Serge

2003-01-01

Lasers are now widely used for treating numerous cutaneous lesions, for scar revision (hypertrophic and keloid scars), for tissue welding, and for skin resurfacing and remodeling (wrinkle removal). In these procedures lasers are used to generate heat. The modulation of the effect (volatilization, coagulation, hyperthermia) of the laser is obtained by using different wavelengths and laser parameters. The heat source obtained by conversion of light into heat can be very superficial, yet intense, if the laser light is well absorbed (far-infrared:CO(2) or Erbium:Yttrium Aluminum Garnet [Er:YAG] lasers), or it can be much deeper and less intense if the laser light is less absorbed by the skin (visible or near-infrared). Lasers transfer energy, in the form of heat, to surrounding tissues and, regardless of the laser used, a 45-50 degrees C temperature gradient will be obtained in the surrounding skin. If a wound healing process exists, it is a result of live cells reacting to this low temperature increase. The generated supraphysiologic level of heat is able to induce a heat shock response (HSR), which can be defined as the temporary changes in cellular metabolism. These changes are rapid and transient, and are characterized by the production of a small family of proteins termed the heat shock proteins (HSP). Recent experimental studies have clearly demonstrated that HSP 70, which is over-expressed following laser irradiation, could play a role with a coordinated expression of other growth factors such as transforming growth factor (TGF)-beta. TGF-beta is known to be a key element in the inflammatory response and the fibrogenic process. In this process, the fibroblasts are the key cells since they produce collagen and extracellular matrix. In conclusion, the analysis of the literature, and the fundamental considerations concerning the healing process when using thermal lasers, are in favor of a modification of the growth factors synthesis after laser irradiation, induced

Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control

KAUST Repository

Sun, Liangfeng; Choi, Joshua J.; Stachnik, David; Bartnik, Adam C.; Hyun, Byung-Ryool; Malliaras, George G.; Hanrath, Tobias; Wise, Frank W.

2012-01-01

Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr '1 m '2) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH 2 groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.© 2012 Macmillan Publishers Limited.

Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control.

Science.gov (United States)

Sun, Liangfeng; Choi, Joshua J; Stachnik, David; Bartnik, Adam C; Hyun, Byung-Ryool; Malliaras, George G; Hanrath, Tobias; Wise, Frank W

2012-05-06

Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr(-1) m(-2)) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH(2) groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.

Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control

KAUST Repository

Sun, Liangfeng

2012-05-06

Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr \\'1 m \\'2) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH 2 groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.© 2012 Macmillan Publishers Limited.

The monitoring system using laser light for the patient movement during radiation therapy

International Nuclear Information System (INIS)

Sano, Naoki; Onishi, Hiroshi; Yamaguchi, Motoshi; Kuriyama, Kengo; Akiyama, Saburou; Nakamura, Osamu; Araki, Tsutomu

1997-01-01

Purpose: The purpose of this study is to evaluate the usefulness of a newly developed real-time patient movement monitoring system built into the patient positioning light from the frontal and horizontal view. Materials and Techniques: This system is composed of 4 parts. They are a laser light projector, a retro-reflected tape, a sensor of photo-diode, and an alarm devise. First, this system projects a laser light for the patient movement monitor into the center of the crossed lines of the patient positioning light. The laser light (a diameter of 1.5mm and power of 0.5mW) for the patient movement monitor has a different wave length(633nm) from the patient positioning light. Then it is reflected into the direction of incidence with a retro-reflection tape affixed on three patient positioning points. And the system has a photo-diode which can sense the reflected laser light. This retro-reflected tape is made of tiny high reflective beads of glass which is fixed on a sheet with the thickness of 0.12mm and is able to be cut into any shape. This has a maximum retro-reflection angle of 70 degrees. We can select a tolerance of the patient movement by changing its shape and size. A buzzer strikes and a lamp is turned on to alarm for the error when the retro-reflected laser light is not sensed with the photo-diode. Results: The real-time monitoring accuracy of this system is only 0.17mm in the dimension of error for a selected tolerance of the phantom examination. Conclusion: This patient positioning system can be made simply and inexpensively and has a high monitoring accuracy. We can apply this system for a high-precision irradiation such as the three dimensional irradiation and small target irradiation

Speckle reduction for a laser light sectioning sensor

Directory of Open Access Journals (Sweden)

Tutsch Rainer

2015-01-01

Full Text Available Automated optical inspection is an important test procedure in electronic circuits assembly. Frequently 3d information is required and laser light sectioning sensors are often applied. However, some effects complicate the reliable automatic detection of the shape of such assemblies and their components. The packages of electronic components often are made of black plastics or ceramics so that the intensity available for the optical detection is quite low, especially in comparison to the surface of the PCBs where the components are mounted on. In addition due to rough surfaces of the components and the coherence length of the laser light speckle structures arise. In the work presented here a piezo actuator is used to oscillate the illuminating laser lines along the direction of the lines. The aim is to reduce the visibility of the speckle structures by averaging while maintaining the geometrical shape of the lines. In addition, image processing methods like segmentation and skeletonization are used to allow the detection of the shape of components and assemblies also if materials with distinct differences in the reflectivity are involved. Investigations include the influence of the parameters amplitude and frequency of the piezo actuator.

Enhanced vacuum laser-impulse coupling by volume absorption at infrared wavelengths

Science.gov (United States)

Phipps, C. R., Jr.; Harrison, R. F.; Shimada, T.; York, G. W.; Turner, R. F.

1990-03-01

This paper reports measurements of vacuum laser impulse coupling coefficients as large as 90 dyne/W, obtained with single microsec-duration CO2 laser pulses incident on a volume-absorbing, cellulose-nitrate-based plastic. This result is the largest coupling coefficient yet reported at any wavelength for a simple, planar target in vacuum, and partly results from expenditure of internal chemical energy in this material. Enhanced coupling was also observed in several other target materials that are chemically passive, but absorb light in depth at 10- and 3-micron wavelengths. The physical distinctions are discussed between this important case and that of simple, planar surface absorbers (such as metals) which were studied in the same experimental series, in light of the predictions of a simple theoretical model.

Room-temperature mid-infrared single-photon imaging using upconversion

DEFF Research Database (Denmark)

Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter; Pedersen, Christian

2014-01-01

The mid-wave infrared (MWIR) region is a fast developing research area due to many possible applications. Indeed a lot of research has been put into the development of novel light sources in the MWIR. This has led to very powerful sources such as quantum cascade lasers (QCL) and optical parametric...... detectors, when compared to silicon based detectors available for the visible and near visible spectral range. In fact, camera sensitivities down to the single photon level have been developed for sub-μm wavelengths. This discrepancy in sensitivity makes it attractive to perform wavelength upconversion...... upconversion efficiencies of 20 % for polarized collinear MWIR light. To make the module truly portable the laser cavity is assembled in a closed mechanical unit which ensures that visible light cannot enter from the outside, and provides a very stable mount for the optical components. Figure 1 depicts...

Simple locking of infrared and ultraviolet diode lasers to a visible laser using a LabVIEW proportional-integral-derivative controller on a Fabry-Perot signal.

Science.gov (United States)

Kwolek, J M; Wells, J E; Goodman, D S; Smith, W W

2016-05-01

Simultaneous laser locking of infrared (IR) and ultraviolet lasers to a visible stabilized reference laser is demonstrated via a Fabry-Perot (FP) cavity. LabVIEW is used to analyze the input, and an internal proportional-integral-derivative algorithm converts the FP signal to an analog locking feedback signal. The locking program stabilized both lasers to a long term stability of better than 9 MHz, with a custom-built IR laser undergoing significant improvement in frequency stabilization. The results of this study demonstrate the viability of a simple, computer-controlled, non-temperature-stabilized FP locking scheme for our applications, laser cooling of Ca(+) ions, and its use in other applications with similar modest frequency stabilization requirements.

Active mode-locking of mid-infrared quantum cascade lasers with short gain recovery time.

Science.gov (United States)

Wang, Yongrui; Belyanin, Alexey

2015-02-23

We investigate the dynamics of actively modulated mid-infrared quantum cascade lasers (QCLs) using space- and time-domain simulations of coupled density matrix and Maxwell equations with resonant tunneling current taken into account. We show that it is possible to achieve active mode locking and stable generation of picosecond pulses in high performance QCLs with a vertical laser transition and a short gain recovery time by bias modulation of a short section of a monolithic Fabry-Perot cavity. In fact, active mode locking in QCLs with a short gain recovery time turns out to be more robust to the variation of parameters as compared to previously studied lasers with a long gain recovery time. We investigate the effects of spatial hole burning and phase locking on the laser output.

[Physical treatment methods for acne. Light, laser, photodynamic therapy and peeling].

Science.gov (United States)

Borelli, C; Korting, H C

2010-02-01

The medical treatment of acne is generally sufficient to meet the expectations of acne patients. However, in a number of situations additional therapeutic approaches may be advisable. There are a wide variety of useful physical methods. They range from electromagnetic waves, usually light, to peeling and manual therapy. Phototherapy of acne includes not just visible light but also laser and flash lamp therapy. The present review provides an overview on the evidence. Visible light, in particular blue light, provides an effective option for treatment of inflammatory acne. Photodynamic therapy also is efficacious; however, it should not be used because of an unfavorable risk-benefit ratio. UV treatment of acne is obsolete. Newer studies on the use of a variety of laser systems and flash lamps have demonstrated in part rewarding results.

Laser coupling to reduced-scale targets at NIF Early Light

International Nuclear Information System (INIS)

Hinkel, D E; Schneider, M B; Young, B K; Holder, J P; Langdon, A B; Baldis, H A; Bonanno, G; Bower, D E; Bruns, H C; Campbell, K M; Celeste, J R; Compton, S; Costa, R L; Dewald, E L; Dixit, S N; Eckart, M J; Eder, D C; Edwards, M J; Ellis, A D; Emig, J A; Froula, D H; Glenzer, S H; Hargrove, D; Haynam, C A; Heeter, R F; Henesian, M A; Holtmeier, G; James, D L; Jancaitis, K S; Kalantar, D H; Kamperschroer, J H; Kauffman, R L; Kimbrough, J; Kirkwood, R K; Koniges, A E; Landen, O L; Landon, M; Lee, F D; MacGowan, B J; Mackinnon, A J; Manes, K R; Marshall, C; May, M J; McDonald, J W; Menapace, J; Moses, S I; Munro, D H; Murray, J R; Niemann, C; Pellinen, D; Power, G D; Rekow, V; Ruppe, J A; Schein, J; Shepherd, R; Singh, M S; Springer, P; Still, C H; Suter, L J; Tietbohl, G L; Turner, R E; VanWonterghem, B M; Wallace, R J; Warrick, A; Watts, P; Weber, F; Wegner, P J; Williams, E A; Young, P E

2005-01-01

Deposition of maximum laser energy into a small, high-Z enclosure in a short laser pulse creates a hot environment. Such targets were recently included in an experimental campaign using the first four of the 192 beams of the National Ignition Facility [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technology 26 26, 755 (1994)], under construction at the University of California Lawrence Livermore National Laboratory. These targets demonstrate good laser coupling, reaching a radiation temperature of 340 eV. In addition, the Raman backscatter spectrum contains features consistent with Brillouin backscatter of Raman forward scatter [A. B. Langdon and D. E. Hinkel, Physical Review Letters 89, 015003 (2002)]. Also, NIF Early Light diagnostics indicate that 20% of the direct backscatter from these reduced-scale targets is in the polarization orthogonal to that of the incident light

Dye laser light for high-resolution classical photography

International Nuclear Information System (INIS)

Geissler, K.K.

1982-01-01

The test run with the bubble chamber HOLEBC in October 1981 offered the opportunity of checking the usefulness of de-speckled dye laser light for illumination purposes in high-resolution classical dark field photography of small bubble chambers. (orig./HSI)

Human dental enamel and dentin structural effects after Er:YAG laser irradiation.

Science.gov (United States)

Lima, Darlon Martíns; Tonetto, Mateus Rodrigues; de Mendonça, Adriano Augusto Melo; Elossais, André Afif; Saad, José Roberto Cury; de Andrade, Marcelo Ferrarezi; Pinto, Shelon Cristina Souza; Bandéca, Matheus Coelho

2014-05-01

Ideally projected to be applied on soft tissues, infrared lasers were improved by restorative dentistry to be used in hard dental tissues cavity preparations--namely enamel and dentin. This paper evidentiates the relevant aspects of infrared Erbium laser's action mechanism and its effects, and characterizes the different effects deriving from the laser's beams emission. The criteria for use and selection of optimal parameters for the correct application of laser systems and influence of supporting factors on the process, such as water amount and its presence in the ablation process, protection exerted by the plasma shielding and structural factors, which are indispensable in dental tissues cavity preparation related to restorative technique, are subordinated to optical modifications caused by the interaction of the energy dissipated by these laser light emission systems in the targeted tissue substrate. Differences in the action of infrared Erbium laser system in regard to the nature of the ablation process and variations on the morphological aspects observed in the superficial structure of the target tissue irradiated, may be correlated to the structural optical modifications of the substrate produced by an interaction of the energy propagated by laser systems.

Polarization effects in above-threshold ionization with a mid-infrared strong laser field

Science.gov (United States)

Kang, Hui-Peng; Xu, Song-Po; Wang, Yan-Lan; Yu, Shao-Gang; Zhao, Xiao-Yun; Hao, Xiao-Lei; Lai, Xuan-Yang; Pfeifer, Thomas; Liu, Xiao-Jun; Chen, Jing; Cheng, Ya; Xu, Zhi-Zhan

2018-05-01

Using a semiclassical approach, we theoretically study the above-threshold ionization of magnesium by intense, mid-infrared laser pulses. The formation of low-energy structures in the photoelectron spectrum is found to be enhanced by comparing with a calculation based on the single-active electron approximation. By performing electron trajectory and recollision-time distribution analysis, we demonstrate that this phenomenon is due to the laser-induced ionic core polarization effects on the recolliding electrons. We also show that the polarization effects should be experimentally detectable. Our finding provides new insight into ultrafast control of strong-field photoionization and imaging of polar molecules.